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Biomedical subjects

V I Shvets

Publications and source records attributed to V I Shvets.

At least 19 recordsLinked to original sources
PubMed2005

Antiviral activity of liposomal preparations of antibiotic geliomycin.

A liposomal preparation with maximally possible content of incorporated geliomycin was obtained. Its cytotoxicity was studied in a culture of human embryonal diploid fibroblasts. Antiviral activity was studied on a model of cytomegaloviral infection in vitro by the capacity to plaque formation. Liposomal geliomycin was 10-fold less toxic for human cells than the solution of the antibiotic in DMSO and exhibited antiviral activity towards cytomegaloviral infection at a concentration of 0.042 microg/ml.

Antiviral Agents↗
PubMed2005

Interaction of rifabutin with model membranes.

Liposomal and free rifabutin were separated by the method of gel filtration. The percents of rifabutin bound to liposomes of different phospholipid composition were measured. The presence of negatively charged phospholipids increased the degree of binding. Binding decreased with increasing the ionic strength. Incubation of rifabutin with liposomes containing anthryl phosphatidylcholine was accompanied by fluorescence quenching. Activity of rifabutin depended on the phospholipid composition of liposomes. Our results indicate that binding of rifabutin is associated with electrostatic and hydrophobic interactions.

Adsorption↗
PubMed2005

[Dependence of rifabutin properties and liposome entrapment on pH of the medium].

Rifabutin solubility within pH 3.0 to 11.0 was determined. Potentiometry, spectrophotometry and computation revealed ionization of three groups with pKa 3.5, 6.5 and 9.5 in the rifabutin molecule. On the basis of the pKa values of certain fragments of the rifabutin molecule computed by the ACD/pKa programme they were related to ionization of the following groups: imidazole residue nitrogen, aromatic hydoxyl and piperidin nitrogen respectively. Interaction of rifabutin with model membranes, i. e. large unilamellar vesicules was studied. At lower pH of the medium, entrapment of rifabutin to the large unilamellar vesicules increased that was evident of satisfactory correlation with the decrease in the rifabutin distribution coefficient in the system multilamellar vesicules/water under the experimental conditions.

Antitubercular Agents↗
PubMed2004

Incorporation of isoniazid into liposomes with different lipid composition.

Liposomes containing isoniazid were obtained by extrusion of multilamellar phospholipid vesicles containing isoniazid, by ultrasound treatment, and from proliposomes. Optimal conditions for isolation of stable liposomes (200 nm in diameter) and the amount of incorporated isoniazid were determined by varying concentrations of phospholipids and isoniazid and by changing phospholipid composition.

Antitubercular Agents↗
PubMed2001

Complexing of basic pancreatic proteinase inhibitor with soybean phospholipid multilamellar vesicles.

The formation of complexes of basic pancreatic proteinase inhibitor (BPTI) with multilamellar vesicles (MLV) from six preparations of soybean phospholipids of various composition was studied. When BPTI, a non-membrane protein, interacts with MLV, the vesicles aggregate, forming a precipitate of protein-lipid complexes. The BPTI content in the protein-lipid complexes increases with decreasing pH of the medium and on addition of negatively charged components into the lipid mixture. The protein-induced aggregation of the phospholipid vesicles is suggested to be mainly determined by electrostatic forces. The antiproteinase activity of BPTI in the complexes was rather low but increased up to 70% of the initial activity on addition of an ionic detergent (sodium deoxycholate).

Aprotinin↗
PubMed2001

Synthesis and properties of bacteriorhodopsin analogs containing electron-density labels in the chromophore moiety.

A method for synthesis of retinal analogs labeled with electron-density groups is suggested. The interaction of these polyene compounds with bacterioopsin in apomembrane of Halobacterium salinarum was tested. A retinal analog containing a crown-ether receptor group is able to interact readily with bacterioopsin giving rise to rapid formation of a pigment with absorption maximum at 460 nm. This pigment is capable of undergoing cyclic photoconversion. The crown-bacteriorhodopsin photocycle is extremely slow and its quantum efficiency is very low (approximately 3% of that in native bacteriorhodopsin). This photocycle includes an M-like intermediate with a differential absorption maximum at 380 nm. A retinal analog in which the beta-ionone ring is replaced by ferrocene moiety forms a stable chromoprotein with the main absorption band at 483 nm and a shoulder near 590-610 nm.

Bacteriorhodopsins↗
PubMed2001

Action of nonviral gene delivery vectors on human complement system: low anticomplementary activity of lipoplexes based on lacZ plasmid and phospholipid/oligocation liposomes.

A simple test-system has been developed for the first time in order to detect the ability of effectors (lipoplexes) to activate the complement system in an antibody-independent manner to serve as acceptors of nascent C4b and to inhibit formation of the key enzyme of complement, C3-convertase. The effect of plasmid DNA (pCMV-SPORT-LacZ), negatively charged cardiolipin (CL), neutral phosphatidylcholine (PC) vesicles and their lipoplexes, on the complement system was studied using the method developed. It was revealed that PC vesicles did not affect the complement system, while CL vesicles manifested low activation. The influence of plasmid DNA and its lipoplex based on PC liposomes as well on the complement system was very low. PC/LacZ lipoplex (143 microg/ml) acted on the complement system like 5.36 microg/ml heat aggregated IgG (agg) (the level of no pathological ruptures), whereas CL/LacZ lipoplex (143 microg/ml) acted similar to 10.7 microg/ml IgG (agg). Thus, weak activation of the complement system with CL lipoplex, and even weaker for the PC lipoplex testified to the use of neutral and positively charged lipoplexes preferably in gene therapy protocols. The technique can also be used for testing the influence of injectable gene therapy vectors on the complement system.

Animals↗
PubMed2000

[The inhibition of complement-dependent hemolysis of liposomes containing cerebroside sulfate].

Cerebroside sulfate (CGS) was found to be capable of inhibiting complement-dependent hemolysis. The activity dependence of CGS-containing liposomes on their composition was studied. Mixtures of CGS with phosphatidylethanolamine, phosphatidylserine, sphingomyelin from cattle brain, cerebroside from cattle spinal cord (CG), and egg yolk phosphatidylcholine (ePC) were investigated. In the case of binary CGS/ePC mixtures, the antihemolytic activity varied nonlinearly with an increase in the mass part of CGS: it sharply increased with an increase in the CGS part from 0.3 to 0.5 and decreased by 20-30% of the maximum value with an increase in the CGS part from 0.9 to 1. On the basis of these experiments, the optimum distance between the charged groups of CGS was estimated to be 0.92-1.6 nm. In the ternary compositions of 4:3:3 CGS/ePC/polar lipid, only CG increased the activity of liposomes as compared to that of liposomes from the 4:6 CGS/ePC. The preliminary incubation of CGS-containing liposomes with complement decreased hemolysis more effectively than incubation with other components of the hemolytic system. This suggests that the interaction of CGS-containing liposomes with the complement proteins is responsible for their antihemolytic activity.

Animals↗
PubMed2000

Interaction of trypsin with multilamellar vesicles of soybean lipids.

The pH dependence of complex formation of trypsin with multilamellar vesicles (MLV) of soybean lipids has been investigated. The lipids were characterized by the same phospholipid composition, but the content of other lipids differed. Decrease of pH or introduction of negatively charged components into the lipid samples increased trypsin content in the protein-lipid complexes. This suggests electrostatic interaction between the protein and soybean lipids. The dependence of trypsin activity in the complexes with MLV on their concentration and on the presence of an ionic detergent was studied. Trypsin-MLV interaction did not result in complete inactivation of the protein molecules. Moreover, the effects of dilution and addition of ionic detergent on trypsin activity were additive. Using a fluorescence technique, complex formation with MLV was found to stabilize trypsin molecules, preventing their autolysis.

Chromatography, Thin Layer↗
PubMed2000

[Chemical synthesis of 15N-labeled zervamicins IIB].

Analogues of 16-membered peptide antibiotic zervamicin IIB with the Gln3 and Gln11 residues 15N-labeled at the C alpha-atoms were synthesized by coupling the antibiotic segments (1-4), (5-9), and (10-16). In turn, these were prepared by a stepwise chain elongation in solution starting from their C-termini using benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) as an activating agent. The sterically hindered 2-aminoisobutyric acid was introduced by the BOP-dimethylaminopyridine system with the preactivation of the carboxyl component. The segment condensation was performed with the use of the 6-trifluoromethylbenzotriazol-1-yloxy-tris(pyrrolidino)phosphonium hexafluorophosphate activating reagent. The homogeneity of the resulting zervamicin analogues was confirmed by HPLC, and their structures were proved by NMR spectroscopy and FAB mass spectrometry.

Anti-Bacterial Agents↗
PubMed1999

Synthesis and intermembrane transfer of pyrene-labelled liponucleotides: ceramide phosphothymidines.

Phospholipid conjugates of 3'-azido-3'-deoxythymidine (AZT) show activity against human immunodeficiency virus (HIV) in vitro. Here we report on the synthesis and characterization of two pyrene containing conjugates: 2-N-(4-(pyren-1-yl)butanoyl)ceramide 5'-phosphothymidine (Pbs-Cer-P-T) (XII) and 2-N-(10-(pyren-1-yl)decanoyl)ceramide 5'-phosphothymidine (Pds-Cer-P-T) (XIII). These fluorescent labelled conjugates served as model compounds to study incorporation of sphingoliponucleotides into membranes. The complex compounds were prepared by condensation of 3'-acetylthymidine and labelled ceramides using the phosphite triester coupling procedure. UV absorption, fluorimetry as well as 1H-, 31P-, 13C-NMR analyses were used for structure confirmation of the synthesized substances. When incorporated into small unilamellar 1-palmitoyl-2-oleoyl-glycerophosphatidyl-choline (POPC) vesicles and incubated with unlabelled acceptor POPC vesicles, the compounds (XII) and (XIII) exhibited spontaneous transfer. Kinetic data suggest that transfer from donor to acceptor vesicles occurred via the intervening aqueous phase. The non-specific lipid transfer protein from bovine liver stimulated the transfer of Pds-Cer-P-T between phospholipid vesicles in a concentration dependent manner.

Animals↗
PubMed1999

[The ways of designing new-generation medicinal and biochemical agents by using ligand-receptor interactions for active membrane transport].

A new approach to designing drugs having antiviral, anticancer, and, possibly, other biological activities is presented. These compounds were designed by choosing the molecular systems having a capacity for biospecific transport across the membranes to the target cells. The compounds containing both pharmacologically active ("pharmacophores") groups and structural fragments of the ligands ensuring recognition, binding to receptor sites, as well as transmembranous transport to the target cells. The molecules comprises the clusters capable to be the substrates of the enzymes eliminating "pharmacophores" near the target cell. A number of the synthesized compounds exhibited a noticeable biological (including antiviral) activity.

Biological Transport↗
PubMed1999

[Concentrating dopamine in liposomes using transmembrane gradient of ammonium sulfate].

The active loading of liposomes from egg phosphatidylcholine and cholesterol with dopamine using an ammonium sulfate gradient was studied. Our conditions allowed the enrichment of the monolamellar liposomes with 90% dopamine added to the medium and, thus, considerably improve the dopamine/lipid ratio. Dopamine-containing liposomes with tocopherol in their lipid bilayer were shown to be stable for 3 weeks.

Ammonium Sulfate↗
PubMed1999

[Preparation and certain properties of the liposomal substance 2,4-di(1-methyl-3-hydroxybutyl)deuteroporphyrin-IX].

A liposome preparation of a porphyrin photosensitizer for photodynamic therapy of tumors (PDT) was obtained. The in vitro efficiency of the photosensitizer was enhanced 2.5-fold through the liposome formulation. The composition and some properties of the new preparation were studied. An algorithm for a complex approach to the prediction of photosensitizer efficiencies by model experiments in vitro was developed. This approach is based on the use of two models: the determination of coefficient of distribution between n-octanol and a phosphate buffer, pH 7.4, and the determination of the cytotoxic effect on the culture of CaOv ovarian adenocarcinoma cells.

Adenocarcinoma↗
PubMed1998

[Physico-chemical properties of borate derivatives of DOPA, dopamine, and their liposome forms].

To increase the solubility of L-3,4-dihydroxyphenylalanine (DOPA) and dopamine (DA) incorporated in liposomes, it was suggested to convert them into ammonium and 1-adamantylammonium borate complexes. The structure of these complexes was studied by 11B and 1H NMR, IR, and mass spectrometry and conductometry. The liposomic form of the complexes is characterized by a high active compound/lipid molar ratio (0.5). Catechols in the form of complex salts are retained better within the inner volume of liposomes.

Amantadine↗