[Effect of tetrahydrocortisol-apolipoprotein A-I complex on protein biosynthesis in hepatocytes and secondary structure of eukaryotic DNA].
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Animals↗
Biomedical subjects
L E Panin
Publications and source records attributed to L E Panin.
[Anomalous change in the specific conductivity in lipoproteins at around physiologic temperatures].
Studying the temperature dependence of conductivity sigma of rat and human lipoproteins and apoprotein A-I fractions revealed an anomalous region in the range of temperatures (35-38) +/- 0.5 degree C. The activation energy delta H and temperature coefficient sigma (delta sigma/delta T) on both sides of Tc and the heat of transition (delta H of transition) were calculated. In high-density human lipoproteins and apoA-I, the delta H value was found to be very low. Some mechanisms of interaction of hydrocortizone with high-density lipoproteins and apoA-I were studied by using IR-spectroscopy and conductometry were studied. It was found that the hormone considerably increases the portion of alpha-helices and beta-structures in these proteins (coil<-->alpha-helix and coil<-->beta-structure transitions). In this case, delta H value of the transition increases 13-fold; in addition, the abnormal region in apoA-I shifts 1-2 degrees C downwards. The anomalous changes in conductivity in the range of physiological temperatures in all lipoprotein fractions including apoA-I are probably related to structural phase transitions both in proteins and in phospholipids. Since the delta H value of the transition in human high-density lipoproteins is small, it is assumed that, in phospholipids of these particles, an orientation transition of the A<-->C smectic type takes place, which is assigned to the second-order phase transition. The structural transition in apoA-I can probably also be assigned to the second-order phase transition since the enthalpia of the transition is very small; presumably, this transition is related to changes in symmetry due to changes in the secondary structure (coil<-->beta-tructure transition).
Animals↗
[Interaction of eukaryotic DNA with apolipoprotein A-I and its complexes with glucocorticoids].
A biochemically active complex of apolipoprotein A-I with tetrahydrocortisol was revealed, which increases gene expression in hepatocytes. It was shown by the method of fluorescent probe that titration of rat liver DNA by the apolipoprotein A-I-tetrahydrocortisol complex leads to the appearance of single-stranded fragments. The effect of the complex on the secondary structure of native DNA was confirmed by the method of small-angle X-ray scattering. It was shown that approximately 54 apolipoprotein A-I molecules carrying tetrahydrocortisol as a ligand bind to one molecule of isolated native DNA, inducing a break of hydrogen bonds between the pair of nitrous bases. It is concluded that the cooperative effect of high-density lipoproteins and cortisol in the regulation of gene expression in hepatocytes with the participation of resident liver macrophages is accomplished by a new biochemical mechanism. This mechanism makes itself evident as a result of the interaction of DNA with the apolipoprotein A-I-tetrahydrocortisol complex, the appearance of single-stranded DNA regions in binding sites, and subsequent initiation of gene transcription.
Animals↗
[Effect of Kupffer cell stimulation by lipopolysaccharides on hepatocyte nuclei].
Metabolism of colloid gold labelled high and low density lipoproteins (LP) in the liver is related to receptor endocytosis in sinusoidal cells. In endotheliocytes, LP are carried to Disse's space primarily in endosomas, in macrophages--as a part of secondary lysosomas. The former variant of transcytosis may be unrelated to structural LP changes while the latter may be associated with their enzymic modification. LP endocytosis enhances in response to stimulation of macrophages with lipopolysaccharides, especially as concerns high density LP of subclass 3 (HDLP-3). In these conditions, hepatic sinusoidal cell uptake of LDLP and HDLP-3 together with glucocorticoids activates nuclear apparatus of hepatocytes, i.e. creates conditions for intensive protein synthesis.
Animals↗
[Immunochemical homology of HIV-1 envelope proteins and human apolipoprotein AI].
Immunochemical homology of envelope HIV proteins and human apolipoprotein A-I was for the first time detected by ELISA. Immunochemical reactions between antibodies to apoA-I and HIV envelope proteins and between apoA-I and anti-HIV antibodies present in the blood of AIDS patients were shown. These data suggest that the homology of surface HIV proteins and human apoA-I can lead to competitive relationships impeding the involvement of human apoA-I in gene expression regulation.
Acquired Immunodeficiency Syndrome↗
[Specific alterations in the secondary structure of eukaryotic DNA effected by a tetrahydrocortisol-apolipoprotein A-I complex].
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Animals↗
[Interaction of tetrahydrocortisol-apolipoprotein A-I complex with eukaryotic DNA and with single-stranded oligonucleotides].
The complex formed by tetrahydrocortisol (THC) and apolipoprotein A-I (ApoAI) specifically interacts with eukaryotic DNA from rat liver. Taken together, physical and chemical data and the results of small-angle X-ray scattering analysis show that interaction of the THC-ApoAI complex with eukaryotic DNA results in deformation of the DNA double helix. Single-stranded fragments were demonstrated to cause deformation of the double helix. In this state DNA forms complexes with DNA-dependent RNA polymerase. This interaction is cooperative and of saturating type; up to six enzyme molecules bind with one DNA molecule. The putative site of complex binding with DNA is the sequence CC(GCC)n found in many genes including the human ApoAI gene. An oligonucleotide of this type was synthesized. Its association constant (Ka) was 1.66 x 10(6) M-1. Substitution of THC with cortysol considerably decreases the Ka. We suggest that THC interacting with GC pairs of the binding site forms hydrogen bonds with cytosine, inducing rupture of the bonds within the complementary nucleic base pair.
Animals↗
[Interaction of human apolipoprotein AI and HIV-1 envelope proteins with the native and recombinant CD4 receptors].
The method of enzyme-linked immunosorbent assay (ELISA) was used to show an interaction of soluble recombinant CD4-receptor (rsCD4) with human apolipoprotein A-1. Competitive interactions between envelope proteins VIH-1 (gp120 and gp41), on the one hand, and human apolipoprotein A-1 with CD4 receptor, present in the cellular membranes of line MT4 human lymphocytes, were demonstrated by the method of flow cytofluorimetry. It was suggested that the competitive interactions between the above proteins could manifest in respect to the apolipoprotein A-1 receptor, which affects the involvement of the latter in the regulation of protein biosynthesis and which leads to a decrease in the body weight of HIV-infected patients.
Apolipoprotein A-I↗
[The prediction of the work capacity of flight operators with different levels of anxiety].
It was shown that due to a high body reserve potential the fatigue in low anxious flight operators (LA) occurs only by the 5th-6th post-leave months and in highly anxious flight operators (HA) it develops already by the 3rd post-leave month. Such pattern of developing the fatigue in flight operators enables one to conclude that the "critical months" for flight safety can be the 3rd and 5th post-leave months in HA and LA flight operators, respectively. It is just these months during which the flight operators should be rehabilitated at the preventorium. The recovered body reserves are determined from such criteria as the return of working capacity (based on correction test data), arterial hemodynamics and especially erythrocytes resistance to the baseline levels during the first post-leave month.
Adult↗
[Features of interaction of complexes cortisol-apolipoprotein A-I and tetrahydrocortisol-apolipoprotein A-I with eukariotic DNA].
On primary culture of hepatocytes it is shown, that a complex cortisol-apolipoprotein A-I did not change rate of biosynthesis DNA and protein, whereas the complex tetrahydrocortisol-apolipoprotein A-I (THC-apoA-I) essentially raised rate of incorporation 3H-thymidine in DNA and 14C-leucine into protein. By a method of small-angle X-ray scattering it is shown, that appreciable interaction with eukariotic DNA is marked only in case of use of a complex THC-apoA-I, thus there is local fusion of DNA. The most probable region of interaction of the given complex with DNA is repetition (GCC)n the type, included in structure of many genes eukariot, including the human. It is synthesized oligonucleotid (duplex) of this type. It is shown, that at his interaction with complex THC-apoA-I there is a formation of more difficult complex, which breaks up with formation of complementary chains of oligonucleotides. The last also enter interaction with complex THC-apoA-I. It is given of kinetic this multiphasic process. Interaction of a complex cortisol-anoA-I with a duplex is less specific and does not result reduce in decay of the duplex and in formation of complementary oligonucleotides.
Animals↗
[Determination of apoprotein A-1 by immunoenzyme analysis].
Indirect solid-phase immunoenzymatic assay was improved and adapted for quantitative estimation of apo A-I in blood serum. Immunochemical identification of apo A-I was carried out and specific antibodies were obtained. Various procedures of blood serum pretreatment affected dissimilarly the detection of antigenic determinants in apo A-I. Presence of tetramethyl urea in blood serum increased by 30% the latent antigenic determinants accessibility.
Antibodies↗
[Pancreatic glycosaminoglycans in acute pancreatitis].
Content of glycosaminoglycans was increased in pancreas of rats with acute pancreatitis. With development of the disease not only content of glycosaminoglycans but heterogeneity of their molecules were increased. This suggests that carbohydrate chains of glycosaminoglycans were degraded; the rate of degradation correlated with severity of pancreatitis.
Acute Disease↗
[Changes in blood lipids in humans during long-term ski crossing in the Extreme North].
Serum lipids were measured in the men who made two ski crosses in the Far North during polar night. The first trip, which was to train the athletes, took 17 days and the second took 38 days. In both studies, lipid mobilization and utilization increased, which led to changes in the lipid spectrum: decrease of the concentration of LDL and, in the second trip, of VLDL and HDL3, and increase of the concentration of HDL2 and cholesterol HDL. In the second trip, lipids were most intensively utilized: lipolysis enhanced and free fatty acids declined. This was also indicated by an increase of the capillary-venous difference in terms of the total fraction of LDL and VLDL as well as free fatty acids. At the end of the second trip, the positive capillary-venous difference in terms of LDL and VLDL and, accordingly, the negative capillary-venous difference in terms of HDL2 and HDL3 increased. At the end of both trips the synthesis of transport lipids grew; in the most strenuous second trip, their active utilization in the working organs was stronger.
Adult↗
[Interaction of lipoproteins in blood serum with steroid hormones].
Interaction of human and serum lipoproteins with steroid hormones (corticosterone and cortisol) was studied. Methods of fluorescence quenching titration and equilibrium dialysis were used for quantitative evaluation of VLDL, LDL and HDL glucocorticoid-binding ability. Association constants were found to be 0.6-2.0 x 10(6) M-1 for corticosterone and 4.0-8.0 x 10(6) M-1 for cortisol. The number of binding sites varied from 3 to 300 for different classes of lipoproteins.
Hormones↗
[Features of oxidation of reserve lipids in liver mitochondria during starvation: the role of non-heme iron and free radical fatty acid oxidation].
Structure-functional transformation fo respiratory chain, developed in response to 72 hrs starvation involved the following alterations: 1. in mitochondria of starved rats distinct increase ws observed in sensitivity of palmitocarnitine oxidation, but not of succinate, to benzhydroxamic acid--chelator of non-heme iron; 2. as compared with controls accumulation of malonic dialdehyde was completely inhibited in liver mitochondria of the starved rats in presence of benzhydroxamic acid; 3. considerable alteration in sensitivity of respiration and ATP synthesis to the effect of some inhibitors was found in liver mitochondria of starved rats. Results of the experiment are discussed on the basis of the assumption that existence of additional pathways of ATP synthesis, essential for adaptation-restoration processes, is biologically important under conditions of stress.
Adenosine Triphosphate↗
[Use of circadian rhythms for analysis of the interrelationships between the concentration of glucocorticoids in the blood and the activity of key enzymes for gluconeogenesis in the liver and kidney of rats].
Circadian rhythms of alterations in content of 11-hydroxycorticosteroids and glucose in blood as well as in the activity of phosphoenolpyruvate carboxykinase, fructose-1,6-diphosphatase and glucose-6-phosphatase in liver and kidney tissues were studied under normal and inverted luminous regimens in summer and winter seasons. These patterns were distinctly altered depending on circadian rhythms in the above-mentioned conditions. The maximal content of 11-hydroxycorticosteroids in blood did not correlate with the highest activity of the gluconeogenesis key enzymes in the periods studied. Daily alterations in the activity of phosphoemolpyruvate carboxykinase were shown to be similar to that of the fructose-1,6-diphosphatase in various tissues at different seasons. But glucose-6-phosphatase differed distinctly from these enzymes by the daily rhythm of activity. This suggests that glucose-6-phosphatase has the other mechanism for regulation of its daily rhythm.
11-Hydroxycorticosteroids↗
[Evaluation of the binding of benzo-a-pyrene by blood serum lipoproteins using the cellulose disk method].
A simple and convenient method has been developed for evaluation binding capacity of lipophilic ligands with lipoproteins or other transport proteins. For this purpose cellulose discs (Whatman 3 MM) were loaded with the constant quantity of 3H-benzopyrene and increasing amounts of unlabelled benzo[a]pyrene in dimethylsulfoxide, dried up and incubated in solution of lipoproteins. Dissociation constants were deduced from the remained disk radioactivity using the Scatchard plot method. The obtained values of the dissociation constants were: HDL--4.1 x 10(-5) M; LDL--1.5 x 10(-6) M; VLDL--8.8 x 10(-6) M.
Animals↗
[Effect of resident macrophages on protein biosynthesis in the liver under conditions of reparative regeneration after partial hepatectomy].
In reparative regeneration of the liver after partial hepatectomy stimulation of the resident macrophages by lipopolysaccharides increases sharply the rate of 14C-leucine inclusion into total protein and into the soluble protein of the tissue supernatant. It is shown that synthesis not only of proteins necessary for restoration of the structural intactness of the liver increases but also of some blood serum proteins: total protein, protein of very low-density and low-density lipoproteins (VLDL and LDL) and of high-density lipoproteins (NDL2). The specific radioactivity of HDL3 protein reduces under such conditions. Increased protein biosynthesis in the liver under the effect of lipopolysaccharides precedes and contributes to intensification of the proliferative activity of the tissue of the damaged liver.
Animals↗