Study of acute and subacute action of iron-molybdenum nanocluster polyoxometalates

There were no significant deviations from the norm in the functional state of the liver, kidneys, and pancreas in the study of the acute toxicity of iron-molybdenum buckyballs intended for targeted drug delivery. No accumulation of nanoparticles or deviation from the norm in any investigated parameter was detected in the study of subacute toxicity. © 2013 Pleiades Publishing, Ltd

Local anisotropy and giant enhancement of local electromagnetic fields in fractal aggregates of metal nanoparticles

We have shown within the quasistatic approximation that the giant fluctuations of local electromagnetic field in random fractal aggregates of silver nanospheres are strongly correlated with a local anisotropy factor S which is defined in this paper. The latter is a purely geometrical parameter which characterizes the deviation of local environment of a given nanosphere in an aggregate from spherical symmetry. Therefore, it is possible to predict the sites with anomalously large local fields in an aggregate without explicitly solving the electromagnetic problem. We have also demonstrated that the average (over nanospheres) value of S does not depend noticeably on the fractal dimension D, except when D approaches the trivial limit D=3. In this case, as one can expect, the average local environment becomes spherically symmetrical and S approaches zero. This corresponds to the well-known fact that in trivial aggregates fluctuations of local electromagnetic fields are much weaker than in fractal aggregates. Thus, we find that, within the quasistatics, the large-scale geometry does not have a significant impact on local electromagnetic responses in nanoaggregates in a wide range of fractal dimensions. However, this prediction is expected to be not correct in aggregates which are sufficiently large for the intermediate- and radiation-zone interaction of individual nanospheres to become important.Comment: 9 pages 9 figures. No revisions from previous version; only figure layout is change

ROLE OF LEUCOCYTES IN LIVER DAMAGE IN EXPERIMENTAL MODELS OF TYPE 1 AND 2 DIABETES MELLITUS

Diabetes mellitus is a metabolic disorder, which results from insufficient secretion of insulin and/or its action, thus leading to hyperglycemia. Liver damage is known to be among the most common complications of type 2 diabetes mellitus (T2D) and is common in T1D. Comparison of the leukocyte phenotypes in liver tissue with appropriate blood parameters may assess degree of liver damage and search for approaches to correction of liver destruction in diabetes mellitus. Therefore, we aimed for assessment of changes in liver injury markers in blood and the numbers of leucocytes (CD45+ cells), T lymphocytes (CD3+ cells) and macrophages in the liver in experimental models of types 1 and 2diabetes. The experiment was conducted on 30 male Wistar rats. Alloxan at the dose of 170 mg/kg of body weight was used for T1D modeling. To provide a model of T2D, streptozotocin and nicotinamide were injected at the doses of 65 mg/kg, and 110 mg/kg respectively. Intact animals were used as a comparison control. Biochemical, hematological, immunohistochemical and morphometrical methods were used in the study. In T1D and T2D groups, levels of glucose (10.88±0.47 mmol/l and 10.78±0.42 mmol/l) and glycosylated hemoglobin (6.73±0.78% and 6.60±0.20% correspondingly) were rather close to each other and exceeded the values of intact rats (5.20±0.40 mmol/l and 4.07±0.30%). At the same time, the increase in total leucocyte number and fraction of peripheral blood leucocytes against normal levels were more pronounced in the T2D group than in T2D group. In liver of rats from the both diabetic groups, increased numbers of sinusoidal cells, macrophages, CD45+ cells and CD3+ cells relative to intact rats were detected. However, in rats from T1D group, CD45+ cells were distributed, mainly, in the liver parenchyma, whereas in rats in T2D group they showed sinusoidal location. At a similar degree of increasing macrophage numbers, and total CD45+ cells number, higher counts of sinusoidal cells and CD3+ cells, located both in the parenchyma and perivascular area, were found in rats of T2DM group compared with this parameter in T1DM group. An increase in ALT activity confirms a more significant damage to liver cells in animals of the T2DM group, whereas, in T1DM group, an increased AST activity and a less pronounced increase in ALT activity indicate uniformly distributed cytolysis. The results of our study showed, that, despite similar hyperglycemia level, the inflammatory process at the level of the whole organism and local inflammatory process in the liver are more pronounced in the T2DM group. A more significant severity of inflammatory process and liver damage corresponds to increase in sinusoidal cells and CD3+ cell infiltration of liver tissue. © 2022 Russian Association of Allergologists and Clinical Immunologists, St. Petersburg Regional Branch (SPb RAACI). All rights reserved

Gamma irradiation impact on electronic carrier transport in AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors were irradiated with Co-60 gamma-rays to doses up to 1000 Gy, in order to analyze the effects of irradiation on the devices\u27 transport properties. Temperature-dependent electron beam-induced current measurements, conducted on the devices before and after exposure to gamma-irradiation, allowed for the obtaining of activation energies related to radiation-induced defects due to nitrogen vacancies. DC current-voltage measurements were also conducted on the transistors to assess the impact of gamma-irradiation on transfer, gate, and drain characteristics

Characteristics of air showers created by extremely high energy gamma-rays

The technique of adjoint cascade equations has been applied to calculate the properties of extremely high energy gamma-rays in the energy range 10^18--10^22 eV with taking into account the LPM effect and interactions of gamma-rays with the geomagnetic field. Such characteristics are analysed as the electron and muon contents at the observation level, the electron cascade curves, the lateral distribution functions of photoproduced muons.Comment: 36 pages, 19 figures, submitted to J.Phys.G: Nucl.Part.Phy

Features of Muon Arrival Time Distributions of High Energy EAS at Large Distances From the Shower Axis

In view of the current efforts to extend the KASCADE experiment (KASCADE-Grande) for observations of Extensive Air Showers (EAS) of primary energies up to 1 EeV, the features of muon arrival time distributions and their correlations with other observable EAS quantities have been scrutinised on basis of high-energy EAS, simulated with the Monte Carlo code CORSIKA and using in general the QGSJET model as generator. Methodically various correlations of adequately defined arrival time parameters with other EAS parameters have been investigated by invoking non-parametric methods for the analysis of multivariate distributions, studying the classification and misclassification probabilities of various observable sets. It turns out that adding the arrival time information and the multiplicity of muons spanning the observed time distributions has distinct effects improving the mass discrimination. A further outcome of the studies is the feature that for the considered ranges of primary energies and of distances from the shower axis the discrimination power of global arrival time distributions referring to the arrival time of the shower core is only marginally enhanced as compared to local distributions referring to the arrival of the locally first muon.Comment: 24 pages, Journal Physics G accepte

Zebrafish Models for Dyskeratosis Congenita Reveal Critical Roles of p53 Activation Contributing to Hematopoietic Defects through RNA Processing

Dyskeratosis congenita (DC) is a rare bone marrow failure syndrome in which hematopoietic defects are the main cause of mortality. The most studied gene responsible for DC pathogenesis is DKC1 while mutations in several other genes encoding components of the H/ACA RNP telomerase complex, which is involved in ribosomal RNA(rRNA) processing and telomere maintenance, have also been implicated. GAR1/nola1 is one of the four core proteins of the H/ACA RNP complex. Through comparative analysis of morpholino oligonucleotide induced knockdown of dkc1 and a retrovirus insertion induced mutation of GAR1/nola1 in zebrafish, we demonstrate that hematopoietic defects are specifically recapitulated in these models and that these defects are significantly reduced in a p53 null mutant background. We further show that changes in telomerase activity are undetectable at the early stages of DC pathogenesis but rRNA processing is clearly defective. Our data therefore support a model that deficiency in dkc1 and nola1 in the H/ACA RNP complex likely contributes to the hematopoietic phenotype through p53 activation associated with rRNA processing defects rather than telomerase deficiency during the initial stage of DC pathogenesis

Localization and distribution of insulin-positive cells in the liver in case of experimental diabetes mellitus

The article considers the localization and distribution of insulinpositive hepatocytes in the simulation of type 1 and type 2 diabetes mellitus. The study was conducted on 25 male Wistar rats weighing 303.0 ± 25.3 g. A type 1 diabetes model was obtained by administering alloxan based on 170 mg / kg rat weight and a type 2 diabetes model by administration of nicotinamide and streptozotocin. Biochemical, immunohistochemical and statistical studies were carried out. When simulating T2DM in animal liver, the number of extrapancreatic insulin- positive cells is significantly higher than with T1DM. In type 1 diabetes,В статье рассмотрены локализация и распределение инсулин-положительных гепатоцитов при моделировании сахарного диабета (СД) 1 и 2 типа. Исследование проводилось на 25 крысах- cамцах линии Wistar массой 303,0±25,3 г. Получены модель СД типа 1 посредством введения аллоксана из расчета 170 мг/кг массы крысы и модель СД типа 2 путем введения никотинамида и стрептозотоцина. Проводились биохимические, иммуногистохимические и статистические исследования. При моделировании СД2 в печени животных количество экстрапанкреатических инсулин-содержащих клеток значительно выше, чем при СД1. Инсулин-положительные гепатоциты при СД1 локализуются преимущественно в области портальных трактов, тогда как при СД 2 типа отмечается их распределение во всех частях печени, в том числе и в портальной област

Physicochemical and biochemical properties of the Keplerate-type nanocluster polyoxomolybdates as promising components for biomedical use

The paper discusses the results of a research on physicochemical and biochemical properties of the Keplerate-type molybdenum-based nanocluster polyoxometalates (POMs), which show promise in the field of biomedicine as a means of targeted drug delivery, including the transport to immune privileged organs. POMs can be considered as components of releasing systems, including the long-acting ones with feedback (for controlling the drug active component release rate). POMs are promising drugs for the treatment of anemia. Also, the paper deals with the results of studies of POM effect on living systems at the molecular and cellular levels, at that of individual organs, and on the organism as a whole. The mechanism and kinetics of POM destruction and possibilities of stabilization, the oscillatory phenomena manifestation, the formation of POM conjugates with bioactive substances which can be released during the destruction of POM, with polymer components, and with indicator fluorescent dyes, as well as forecasts for further research, are considered. © 2021, ITMO University. All rights reserved.The paper was prepared in the framework of implementation of the State Assignment from the Ministry of Education and Science of the Russian Federation (Projects Nos. AAAA-A20-120061990010-7 (FEUZ-2020-0052) and AAAA-A18-118020590107-0), as well as of the Program for Increasing Competitiveness of UrFU (financially supported according to the Decree No. 211 of the Government of the Russian Federation, Contract No. 02.A03.21.0006). The research aimed at creating the long-time drug release systems with feedback was carried out within the framework of the project of the Russian Science Foundation No. 19-73-00177