66 research outputs found
Bound Magnetic Polaron Interactions in Insulating Doped Diluted Magnetic Semiconductors
The magnetic behavior of insulating doped diluted magnetic semiconductors
(DMS) is characterized by the interaction of large collective spins known as
bound magnetic polarons. Experimental measurements of the susceptibility of
these materials have suggested that the polaron-polaron interaction is
ferromagnetic, in contrast to the antiferromagnetic carrier-carrier
interactions that are characteristic of nonmagnetic semiconductors. To explain
this behavior, a model has been developed in which polarons interact via both
the standard direct carrier-carrier exchange interaction (due to virtual
carrier hopping) and an indirect carrier-ion-carrier exchange interaction (due
to the interactions of polarons with magnetic ions in an interstitial region).
Using a variational procedure, the optimal values of the model parameters were
determined as a function of temperature. At temperatures of interest, the
parameters describing polaron-polaron interactions were found to be nearly
temperature-independent. For reasonable values of these constant parameters, we
find that indirect ferromagnetic interactions can dominate the direct
antiferromagnetic interactions and cause the polarons to align. This result
supports the experimental evidence for ferromagnetism in insulating doped DMS.Comment: 11 pages, 7 figure
Uptake of cholesterol esters being a part of the different fractions of blood plasma lipoproteins by rats organs and tissues
The paper deals with the functions of the main classes of blood plasma lipoproteins (LP) that are associated with the transport of cholesterol esters included in their composition. The aim of the study was to investigate the features of the uptake of cholesterol esters associated with plasma LP fractions (very low (VLDL), low (LDL), and high density LPs (HDL)) by rat organs and tissues, and to show the participation of various subfractions of HDL (HDL2 and HDL3) as specific cholesterol carriers in the main steroid-producing organs of rats.Material and methods. The in vivo studies with intravenous LP injection of 14C labeled cholesterol oleate (14C-OCh) associated with plasma LP fractions have been carried out.Results. Intravenous injection of a 14C-OCh) in the composition with VLDL led to the maximal mark uptake by the liver. Three times less uptake of labeled cholesterol was observed in the adrenal glands, testes and heart muscle. In other tissues radioactivity gradually decreased in the raw: spleen > lungs > kidneys > thyroid gland and adipose tissue. After the injection of 14C-OCh in the composition of LDL marked predominant uptake of the label by the adrenal glands, testes, and liver. A feature of the use of HDL as a carrier platform for 14C-OCh is the high accumulation of label in steroid-producing organs: the adrenal glands and testis. The dynamics of uptake of 14C-OCh in the composition of HDL by the adrenal glands and testes of rats in different time intervals after injection (30 min, 3, 6 and 12 h) was studied. Adrenal cells actively uptake 14C-OCh from HDL, as a result of which the radioactivity of the tissue increased rapidly and after 30 minutes almost reached its maximum. In contrast to the adrenal glands uptake of the testis was characterized by a gradual increase in radioactivity with a maximum of 6 hours and a rather sharp decrease to 12 hours from the beginning of the experiment. In vitro experiments showed the differences in the effect of HDL2 and HDL3 on the corticosterone production by the adrenal glands of rats.Conclusions. The paper presents the features of uptake of cholesterol esters by organs and tissues of rats depending on the used LP-transporter (VLDL, LDL, HDL). In addition, the results suggest that HDL3 subfraction may be the more preferred source of cholesterol for steroid synthesis in the adrenal cortex of rats compared to HDL2 subfraction
BLOOD LIPOPROTEINS AS A PLATFORM FOR TRANSPORT OF HYDROPHILIC AND HYDROPHOBIC COMPOUNDS
The paper discusses the transport functions of the main classes of blood plasma lipoproteins (LP) that are not associatedΒ with the metabolism of lipids that make up their composition. The aim of the study was to study the ability of variousΒ plasma LP fractions (very low (VLDL), low (LDL) and high density (HDL)) to interact with certain hydrophilic andΒ hydrophobic compounds and show the role of LP as transport forms of xenobiotics in the organs and tissues of theΒ body. Material and methods. The studies were performed with tritium-labeled cytochalasin B, benzylpenicillin,Β benzanthracene, benzo(a)pyrene, ultracentrifugation of human plasma LP fractions, column chromatography; inΒ vivo experiments with intravenous injection of LP complexes with tritium-labeled benzanthracene were conducted.Β Results. The ability of various classes of LP to form complexes with hydrophilic (cytochalasin B, benzylpenicillin) andΒ hydrophobic (benzanthracene, benzo(a)pyrene) compounds is shown by the method of ultracentrifugation. More thanΒ 50 % of the radioactivity of hydrophilic compounds in human blood plasma was represented in the composition of theΒ LDL and HDL fractions, and in the composition of the VLDL fractions it was minimal β 6.3 and 5.1 %, respectively.Β A significant part of cytochalasin and benzylpenicillin was also present in the protein infranatant β 43.6 and 40.9 %,Β respectively. The distribution in blood plasma for hydrophobic (benzanthracene, benzo(a)pyrene) compounds wasΒ different. More than 80 % of the radioactivity was represented in the composition of the LP fractions. The polar proteinΒ infranatant contained 16.1 % of the radioactivity of benzantracene and 13.6 % of benzo(a)pyrene. The features ofΒ the lipophilic xenobiotics uptake by organs and tissues were shown in vivo experiments with intravenous injection ofΒ complexes of LP with tritium-labeled benzanthracene to rats. The highest specific radioactivity was found in the liverΒ and adrenal glands after the intravenous injection of 3H-benzanthracene in the composition of VLDL and LDL. TwiceΒ less uptake of the labeled drug was observed in the testis and kidneys. Radioactivity decreased in the series: lungs,adipose tissue, thymus, heart, and spleen. A feature of the use of HDL as a platform for 3H-enzanthracene is the intenseΒ accumulation of lipophilic xenobiotics in steroid-producing organs: the adrenal glands and testis. Conclusion. TheΒ results obtained allow us to consider the real possibility of using blood plasma PL as transport platforms for hydrophilicΒ and hydrophobic compounds into the cells of organs and tissues
ΠΠΈΠΏΠΎΠΏΡΠΎΡΠ΅ΠΈΠ½Ρ Π²ΡΡΠΎΠΊΠΎΠΉ ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΠΏΠ»Π°Π·ΠΌΡ ΠΊΡΠΎΠ²ΠΈ ΠΊΠ°ΠΊ ΡΡΠ°Π½ΡΠΏΠΎΡΡΠ½Π°Ρ ΡΠΎΡΠΌΠ° Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½Π° Π
Introduction. The development of new and highly effective antitumor therapy is one of the priorities of pharmacology. The paper presents one of the solutions to the problem related to the development of transport forms of antitumor drugs.The aim of the study was to study the ability of various fractions of plasma lipoproteins (VLDLP, LDL, HDL) to interact with actinomycin D and show the role of HDL as a transport form of actinomycin D in the body cells.Material and methods. The studies were conducted using unlabeled and tritium-labeled actinomycin D, preparative ultracentrifugation of the rat plasma lipoprotein fractions, chromatography, and in vivo experiments with intravenous administration of HDL complexes with labeled actinomycin D.Results. The important role of HDL in the formation of complexes with actinomycin D in comparison with LDL and LPA was shown. The basic physicochemical characteristics of the interaction of HDL and apolipoprotein A-I with actinomycin were obtained. The constants of the association were of the order of 105 M-1, and the number of binding sites for the drug was 26 for HDL and 12 for apolipoprotein A-I. In vivo studies on rats, the highest radioactivity after intravenous injection of HDL complexes with tritium-labelled actinomycin D was observed in the adrenal glands, then in the liver and kidneys. The uptake of tritium-labelled actinomycin D was twice lower in the lungs, adipose tissue, thymus and spleen. The low uptake of the label was observed in the myocardial tissue.Conclusion. The results obtained demonstrate the feasibility of using HDL as a transport form of actinomycin D in body cells.ΠΠ²Π΅Π΄Π΅Π½ΠΈΠ΅. Π Π°Π·ΡΠ°Π±ΠΎΡΠΊΠ° Π½ΠΎΠ²ΡΡ
ΠΈ Π²ΡΡΠΎΠΊΠΎΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΡ
ΡΡΠ΅Π΄ΡΡΠ² ΠΏΡΠΎΡΠΈΠ²ΠΎΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²ΠΎΠΉ ΡΠ΅ΡΠ°ΠΏΠΈΠΈ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΎΠ΄Π½ΠΎΠΉ ΠΈΠ· ΠΏΡΠΈΠΎΡΠΈΡΠ΅ΡΠ½ΡΡ
Π·Π°Π΄Π°Ρ ΡΠ°ΡΠΌΠ°ΠΊΠΎΠ»ΠΎΠ³ΠΈΠΈ. Π ΡΠ°Π±ΠΎΡΠ΅ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ΠΎ ΠΎΠ΄Π½ΠΎ ΠΈΠ· ΡΠ΅ΡΠ΅Π½ΠΈΠΉ Π΄Π°Π½Π½ΠΎΠΉ ΠΏΡΠΎΠ±Π»Π΅ΠΌΡ, ΡΠ²ΡΠ·Π°Π½Π½ΠΎΠ΅ Ρ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠΊΠΎΠΉ ΡΡΠ°Π½ΡΠΏΠΎΡΡΠ½ΡΡ
ΡΠΎΡΠΌ ΠΏΡΠΎΡΠΈΠ²ΠΎΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²ΡΡ
ΠΏΡΠ΅ΠΏΠ°ΡΠ°ΡΠΎΠ².Π¦Π΅Π»Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ - ΠΈΠ·ΡΡΠΈΡΡ ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡ ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
ΡΡΠ°ΠΊΡΠΈΠΉ Π»ΠΈΠΏΠΎΠΏΡΠΎΡΠ΅ΠΈΠ½ΠΎΠ² ΠΏΠ»Π°Π·ΠΌΡ ΠΊΡΠΎΠ²ΠΈ (ΠΠΠΠΠ, ΠΠΠΠ, ΠΠΠΠ) Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΎΠ²Π°ΡΡ Ρ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½ΠΎΠΌ Π ΠΈ ΠΏΠΎΠΊΠ°Π·Π°ΡΡ ΡΠΎΠ»Ρ ΠΠΠΠ ΠΊΠ°ΠΊ ΡΡΠ°Π½ΡΠΏΠΎΡΡΠ½ΠΎΠΉ ΡΠΎΡΠΌΡ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½Π° Π Π² ΠΊΠ»Π΅ΡΠΊΠΈ ΠΎΡΠ³Π°Π½ΠΈΠ·ΠΌΠ°.ΠΠ°ΡΠ΅ΡΠΈΠ°Π» ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ. ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Π²ΡΠΏΠΎΠ»Π½Π΅Π½Ρ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ Π½Π΅ΠΌΠ΅ΡΠ΅Π½ΠΎΠ³ΠΎ ΠΈ ΠΌΠ΅ΡΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΡΠΈΡΠΈΠ΅ΠΌ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½Π° Π, ΠΏΡΠ΅ΠΏΠ°ΡΠ°ΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠ»ΡΡΡΠ°ΡΠ΅Π½ΡΡΠΈΡΡΠ³ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΡΠ°ΠΊΡΠΈΠΉ Π»ΠΈΠΏΠΎΠΏΡΠΎΡΠ΅ΠΈΠ½ΠΎΠ² ΠΏΠ»Π°Π·ΠΌΡ ΠΊΡΠΎΠ²ΠΈ ΠΊΡΡΡ, Ρ
ΡΠΎΠΌΠ°ΡΠΎΠ³ΡΠ°ΡΠΈΠΈ, Π° ΡΠ°ΠΊΠΆΠ΅ Π² ΠΎΠΏΡΡΠ°Ρ
in vivo c Π²Π½ΡΡΡΠΈΠ²Π΅Π½Π½ΡΠΌ Π²Π²Π΅Π΄Π΅Π½ΠΈΠ΅ΠΌ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ² ΠΠΠΠ Ρ ΠΌΠ΅ΡΠ΅Π½ΡΠΌ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½ΠΎΠΌ Π.Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. ΠΠΎΠΊΠ°Π·Π°Π½Π° Π²Π°ΠΆΠ½Π°Ρ ΡΠΎΠ»Ρ ΠΠΠΠ Π² ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠΈ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ² Ρ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½ΠΎΠΌ Π ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ ΠΠΠΠ ΠΈ ΠΠΠΠ. ΠΠΎΠ»ΡΡΠ΅Π½Ρ ΠΎΡΠ½ΠΎΠ²Π½ΡΠ΅ ΡΠΈΠ·ΠΈΠΊΠΎ-Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ ΠΠΠΠ ΠΈ Π°ΠΏΠΎΠ»ΠΈΠΏΠΎΠΏΡΠΎΡΠ΅ΠΈΠ½Π° Π-I Ρ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½ΠΎΠΌ Π. ΠΠΎΠ½ΡΡΠ°Π½ΡΡ Π°ΡΡΠΎΡΠΈΠ°ΡΠΈΠΈ Π±ΡΠ»ΠΈ ΠΏΠΎΡΡΠ΄ΠΊΠ° 105 Π-1, Π° ΡΠΈΡΠ»ΠΎ ΡΠ΅Π½ΡΡΠΎΠ² ΡΠ²ΡΠ·ΡΠ²Π°Π½ΠΈΡ Π΄Π»Ρ ΠΏΡΠ΅ΠΏΠ°ΡΠ°ΡΠ° ΡΠΎΡΡΠ°Π²ΠΈΠ»ΠΎ 26 Π΄Π»Ρ ΠΠΠΠ ΠΈ 12 Π΄Π»Ρ Π°ΠΏΠΎΠ»ΠΈΠΏΠΎΠΏΡΠΎΡΠ΅ΠΈΠ½Π° Π-I. Π ΠΎΠΏΡΡΠ°Ρ
in vivo Ρ Π²Π½ΡΡΡΠΈΠ²Π΅Π½Π½ΡΠΌ Π²Π²Π΅Π΄Π΅Π½ΠΈΠ΅ΠΌ ΠΊΡΡΡΠ°ΠΌ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ² ΠΠΠΠ Ρ ΠΌΠ΅ΡΠ΅Π½Π½ΡΠΌ ΡΡΠΈΡΠΈΠ΅ΠΌ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½ΠΎΠΌ Π ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΡΠ΅ΡΠ΅Π· 30 ΠΌΠΈΠ½ ΠΏΠΎΡΠ»Π΅ Π²Π²Π΅Π΄Π΅Π½ΠΈΡ Π½Π°ΠΈΠ±ΠΎΠ»ΡΡΠ°Ρ ΡΠ΄Π΅Π»ΡΠ½Π°Ρ ΡΠ°Π΄ΠΈΠΎΠ°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π±ΡΠ»Π° ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½Π° Π² Π½Π°Π΄ΠΏΠΎΡΠ΅ΡΠ½ΠΈΠΊΠ°Ρ
, Π·Π°ΡΠ΅ΠΌ Π² ΠΏΠ΅ΡΠ΅Π½ΠΈ ΠΈ ΠΏΠΎΡΠΊΠ°Ρ
. ΠΠ΄Π²ΠΎΠ΅ ΠΌΠ΅Π½ΡΡΠ΅Π΅ ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΠ΅ ΠΌΠ΅ΡΠ΅Π½ΠΎΠ³ΠΎ ΠΏΡΠ΅ΠΏΠ°ΡΠ°ΡΠ° Π½Π°Π±Π»ΡΠ΄Π°Π»ΠΈ Π² Π»Π΅Π³ΠΊΠΈΡ
, ΠΆΠΈΡΠΎΠ²ΠΎΠΉ ΡΠΊΠ°Π½ΠΈ, ΡΠΈΠΌΡΡΠ΅ ΠΈ ΡΠ΅Π»Π΅Π·Π΅Π½ΠΊΠ΅. Π‘Π»Π°Π±ΠΎΠ΅ ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΠ΅ ΠΌΠ΅ΡΠΊΠΈ ΠΎΡΠΌΠ΅ΡΠ΅Π½ΠΎ Π² ΡΠΊΠ°Π½ΠΈ ΠΌΠΈΠΎΠΊΠ°ΡΠ΄Π°.ΠΠ°ΠΊΠ»ΡΡΠ΅Π½ΠΈΠ΅. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΡΡΠΈΡΠ°ΡΡ ΡΠ΅Π°Π»ΡΠ½ΠΎΠΉ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ ΠΠΠΠ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΡΠ°Π½ΡΠΏΠΎΡΡΠ½ΠΎΠΉ ΡΠΎΡΠΌΡ Π°ΠΊΡΠΈΠ½ΠΎΠΌΠΈΡΠΈΠ½Π° Π Π² ΠΊΠ»Π΅ΡΠΊΠΈ ΠΎΡΠ³Π°Π½ΠΈΠ·ΠΌΠ°
Influence of total low dose fractionated radiation on growth and metastasis of mice Lewis lung carcinoma
Effects of prolonged fractionated ionized radiation in low doses on the growth and metastasis intensity of mice Lewis lung carcinoma (LLC) are studied. On the background of tumor growth, stimulation induced by irradiation in the selected mode of dose fractionation inhibition of spontaneous dissemination of tumor cells into lungs is observed. On the 23-rd day after cell inoculation metastases incidence in irradiated animals was 25 % lower; the number and size of lung metastases decreased by 1.6 and 1.7 times. In the remote terms of tumor growth inhibition of functional activity of macrophages β central effectors of non-specific anti-tumor immunity was revealed
THE INFLUENCE OF ENDOTHELIUM-DEPENDENT MECHANISMS OF VESSEL TONE REGULATION ON THE TISSUE OXYGENATION PARAMETERS IN PATIENTS WITH ISCHEMIC STROKE AT THE BACKGROUND OF ARTERIAL HYPERTENSION SYNDROME
Aim. To study properties of tissue oxygenation and role of nitricoxyde-ergic reactions of circulation in ischemic stroke at the background of arterial hypertension. Material and methods. Totally 62 men and women included with the diagnosis of ischemic stroke. All patients underwent CT and MRI of the brain; cerebral flow was studied by extra- and transcranial ultrasound dopplerography, central hemodynamics was assessed by echocardiography, the basic clinical tests performed, and neurological and neuroophthalmological examination. Study of oxygen transport on the microcirculatory level was performed by polarographic method by transcutaneous measurement of oxygen pressure in tissues. Gases of the blood were measured on the analyzer Easy Stat "Medica Corporation" (USA). For the evaluation of nitric oxide (NO) level, we used the measurements of its stabile metabolites on blood β nitrites and nitrates. Neurological status was examined with the NIHSS score (The Score of the National Health Institute of the US, by T Brot, H.R Adams, 1989). All patients studied were then grouped into 3 groups according to severity of the stroke. Mathematical analysis was performed using software "Statistica 6.0" with non-parametric criteria of Mann-Whitney. Significant were the data with p<0,05.Results. In patients with ischemic stroke, there were disorders of nitricoxide-ergic mechanism of the vessels. Decrease of the level of stable NO metabolites and impairment of tissue oxygenation were linked to the severity of the disease and prominence of neurologic deficiency.Conclusion. In ischemic stroke, there are structural and functional changes in cerebral vessels, which do worsen by the impairment of systemic circulation, increase of systemic pressure, those then lead to tissue hypoxia and neurologic deficiency progression
On the theory of carrier-induced ferromagnetism in diluted magnetic semiconductors
Two different approaches (presented in the literature as alternative approximations) to the problem of carrier-induced ferromagnetism in the system of disordered magnetic ions of a diluted magnetic semiconductor are analyzed. They are based on a self-consistent procedure for the mean exchange fields and the RKKY interaction. Calculations in the framework of exactly solvable model are carried out, and it shows that these approaches stem from two different contributions to the magnetic susceptibility. One stems from the diagonal part of the carrier-ion exchange interaction and corresponds to mean field approximation. The other one stems from the off-diagonal part of the same interaction and describes the indirect interaction between localized spins via free carriers. These two contributions can be responsible for the different magnetic properties. Thus, the aforementioned contributions are complementary but not alternative to each other. A general approach is proposed and compared with different approximations to the problem under consideration
- β¦