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Biomedical subjects

G L Grigorian

Publications and source records attributed to G L Grigorian.

At least 19 recordsLinked to original sources
PubMed1992

[Use of spectral characteristics of ryodipine in the study of dihydropyridine receptor complex of neuronal membranes].

A fluorescent dihydropyridine (DHP) derivative, ryodipine, was used to study structural characteristics of the DHP-sensitive Ca-channels in nerve terminals (synaptosomes) isolated from the rat cerebral cortex. It was found that an inductive resonance energy transfer from membrane proteins to ryodipine occurred in synaptosomal membranes. Two groups of membrane proteins differentially accessible to ryodipine were found by quenching of their own fluorescence. The percentage of group I proteins (20%) whose fluorescence was quenched by up to 1 microM ryodipine, was increased by 50% upon K(+)-depolarization and remained unchanged upon the addition of 100 microM Ni2+, whereas the addition of 100 microM Cd2+ prevented the increase induced by K(+)-depolarization. Nifedipine and nicardipine competed with ryodipine for the DHP receptor as evidenced by the change in percentage of group I proteins. The percentage of group II proteins (50% at 10 microM ryodipine) remained unchanged during various functional alterations of the synaptosomal membranes. Model experiments on proteoliposomes demonstrated that binding of ryodipine to synaptosomal membranes was due mainly to the hydrophobicity of DHP but not the ligand-receptor interaction. Nonetheless we that the membrane proteins-ryodipine system could be a qualitative test for the functional state of DHP-sensitive Ca-channels.

Animals↗
PubMed1986

Investigation of membrane proteins in rat erythrocytes in spontaneous hypertension by means of spin-label technique.

It has been suggested that alterations in cell membrane proteins may play a role in changes of erythrocyte membrane structure and function in hypertension. In order to characterize the structure of membrane proteins of erythrocytes from spontaneously hypertensive rats (SHR) the spin-label technique with a maleimide spin-label was used. A significant difference was observed in the characteristic electron-spin resonance (e.s.r.) spectrum of the label between samples from normotensive rats and SHR. The difference was eliminated and the spectrum significantly changed after treatment of the labelled membrane with EDTA followed by washing out the EDTA extracts, whereas the same treatment with EDTA without the following washing had no effect on the e.s.r. spectrum. It is concluded that the EDTA extracts different substances in the different rat groups. The spin-label technique is a useful method for distinguishing cell membrane properties in SHR and normotensive rats.

Animals↗
PubMed1979

[Synthesis of spin-labeled rubomycin and a study of its interaction with DNA].

Hydrochloride of 14-(I-oxyl-2,2,6,6-tetramethylpiperidyl-4)-acetoxyrubomycin (spin-labeled rubomycin or SL-rubomycin) was prepared by interaction of hydrochloride of 14-bromrubomycin with potassium salt of I-oxyl-2,2,6,6-tetramethylpiperidyl-4-acetic acid. Its interaction with DNA and synthetic poly A and poly U polyribonucleotides was studied. The character of the EPR spectra was indicative of DNA binding with SL-rubomycin and forming a system with a high level of regularity similar to that of liquid crystals. The results of the study of the EPR spectra correlated with the model of rubomycin intercalation between the pairs of DNA bases and were indicative of water surrounding of the nitroxyl group of SL-rubomycin bound with DNA.

DNA↗
PubMedDate not supplied

[Adolescents' health in Nagorno-Karabakh].

Some health indices were studied in teenagers in Nagorny Karabakh. The paper presents data on their physical development, hemodynamics, sexual maturity, and total morbidity. There are some regional features in the study indices, which consist in low harmonicity of physical development and hemodynamics, as well as in high morbidity rates with a predominance of cardiovascular and collagen diseases. The found abnormalities may be directly related to the poor environment for teenagers in Nagorny Karabakh after the 1991-1994 war in the region and show it necessary to improve their living conditions, medical control, and therapeutical-and-prophylactic measures.

Adolescent↗
PubMedDate not supplied

[Study of DNA-dye interaction by spin-labels].

The binding of ethidium bromide and acriflavin dyes with DNA modified with a spin-labelled analogue of ethylene imine has been studied. These spin-labels were shown to bind covalently to DNA, at the same time the number of the dye molecules bound is decreased without any changes in the binding constant. Analysis of ESR spectra of the samples in the frozen 50% water-glycerol solution at 77 degrees K for spin-labelled DNA has shown that addition of the dyes increases distance between the labels. This fact might be explained by an increase in DNA length upon formation of the complex with dye molecules.

Acridines↗
PubMedDate not supplied

[Interaction of spin-labeled methacyne analog with butyrylcholinesterase].

Interaction between spin-labeled methacyne (I) and butyrylcholinesterase (BChE) was studied by ESR and enzyme kinetic methods. The compound (I) was shown to be a competitive reversible inhibitor, the value of Ki appeared to be 1.3 X 10(-5) M. Insertion of nitroxyl fragment in the methacyne molecule results in a two-fold increase of its inhibitory activity. The ESR spectrum of the enzyme-inhibitor complex was registered. This complex dissociates under the action of eserine, tetramethylammonium and hexamethonium. Scatchard plot reveals two different types of binding sites with Kdiss values 1.5 X 10(-5) M and 2.6 X 10(-4) M. One type of binding sites is identified as the enzyme active centre. The restricted motion of (I) in complex with BChE proves the assumption that the enzyme active centre is located in the split of macromolecule surface.

Binding Sites↗
PubMedDate not supplied

[Binding of reversible spin-labeled inhibitors with an butyrylcholinesterase active center].

The interaction of spin-labeled metacyn, procaine, carbolin and bivalent cations (Ca2+, Co2+, Ni2+) with butyrylcholinesterase (BChE) was studied by ESR and enzyme kinetic methods. The effect of pH, ionic strength and organic solvent was analysed. Spin-labeled metacyn binds at the anionic site of BChE active centre. This complex is stabilized both with coulombic and hydrophobic interactions, ionizing group of active centre with pK 6-7 also affects the binding. Spin-labeled procaine appeared to be enzyme competitive inhibitor (Ki = 4 X 10(-5) M) and is located, most probably, at the same site. Activating effect of Ca2+ ions on BChE was confirmed. Simultaneous application of spin labels and paramagnetic ions demonstrates that cations Co2+ and Ni2+ bind with BChE in the close vicinity of spin-labeled inhibitor site. Paramagnetic cations are located more closely to the cationic part of the inhibitor molecule than to the hydrophobic one, and can be displaced by surplus of Ca2+ ions. The experimental data testify the model of anionic centre which consists of bivalent metal ions and aminoalcyl cationic group subsites and is located in a hydrophobic pocket of the enzyme surface.

Binding Sites↗