[A comparative study of liposome-incorporated beta-lactam antibiotics, fluoroquinolones and cephalosporin conjugates with fluoroquinolones].

Beta-lactam antibiotics (some penicillins and cephalosporins), a fluorquinolone (pefloxacin) and cephalosporin conjugates with fluorquinolones were liposome-encapsulated by the method of detergent dialysis. Under the experimental conditions the entrapment of the beta-lactams and pefloxacin to liposomes did not exceed 20 and 12.5 per cent of the initial quantity respectively.

[Inactivation of free and liposome-encapsulated aminoglycosides by enzymes of resistant strains of bacteria].

Liposome-encapsulated gentamicin, sisomicin, paromomycin, amikacin, dibekacin and some other aminoglycoside antibiotics were prepared by the method of detergent dialysis. The entrapment level was higher with respect to paromomycin, gentamicin and sisomicin. After a 1-hour incubation of the liposome-encapsulated paromomycin in the presence of a cell-free preparation of 3'-1-phosphotransferase from Escherichia coli there was observed no inactivation of the antibiotic.

[Obtaining liposomal preparations of various biologically active substances by the method of detergent flow analysis].

It was shown that detergent dialysis could be successfully used for liposomal encapsulation of substances belonging to different chemical groups with diverse therapeutic activity such as rifampicin, aclarubicin, amphotericin B, pefloxacin and insulin. Liposome encapsulation of substances poorly soluble or insoluble in aqueous media was likely the most promising. The optimal incorporation depended on both the composition of the lipids forming the liposomes and the properties of the compounds being encapsulated.

[Ultrastructure of liposomes (interliposomal bonds)].

Interliposomal bonds (ILBS) analogous to intercellular bonds (ICBs) in microbial cultures were detected by electron microscopy in the liposomal materials obtained after encapsulation of substances of various chemical structure. Possible nonspecific formation of the bonds between biological membrane-limited objects (ILBs and ICBs) was suggested and formation of such bonds in liposome encapsulated drugs was believed to be of importance.

[Penicillin-binding proteins of various strains of Lactobacillus].

Sensitivity of different species of Lactobacillus i.e. L.

[Effect of aminoglycosides on the binding of C14-benzylpenicillin by penicillin-binding proteins in Escherichia coli].

It was shown that preincubation of E. coli intact cells with gentamicin and streptomycin induced a marked increase in binding of 14C-benzylpenicillin to its final targets in the membrane i.e.

[Competitive binding of various beta-lactam compounds to penicillin-binding proteins of Escherichia coli].

Competing interaction of two novel N-acyl derivatives of ampicillin i.e. N'-benzylchlorbenzimidazole (No.

[Comparative characteristics of penicillin-binding proteins of representatives of the genus Streptomyces].

Penicillin-binding proteins (PBPs) in Strepomyces strains producing clavulanic acid and beta-lactamase and in Streptomyces strains not producing these compounds were studied comparatively. In S. clavuligerus, the organism producing clavulanic acid, there were detected 3 PBPs in the membrane fraction.

[Dynamics of protein biosynthesis in a Streptomyces erythreus culture and its alteration as affected by exogenous erythromycin].

The intensity of protein biosynthesis in cultures of Streptomyces erythreus estimated by the specific incorporation of 2[14C]-valine into the mycelium changed in accordance with a definite irregular rhythm. When the samples were collected every 6 hours a number of pronounced radioactivity peaks characterizing the intensity of the label incorporation was observed. The height of the peaks was different and they were recorded at different intervals during both the phase of the culture intensive growth and the stationary phase.

[Aminoglycoside acetyltransferase from Streptomyces fradiae--a producer of neomycin].

An enzyme inactivating aminoglycosides by acetylation was isolated from S. fradiae 918 producing neomycin. By the data on the substrate specificity the enzyme was identified as aminoglycoside-3-acetyltransferase.

[Cooperative functioning of 2 systems of protection against its own antibiotic in Str. erythreus 1571, a superproducer of erythromycin].

Protein synthesis in the mycelium of various ages and the protoplasts of Str. erythreus 1571 was slightly sensitive even to high concentrations of erythromycin and lincomycin. Oxytetracycline and neomycin in low concentrations induced marked inhibition of the protein synthesis.

[Effect of lincomycin and other protein synthesis inhibitors on the metabolism of Actinomyces roseolus, a producer of lincomycin].

The ability of lincomycin, erythromycin and oxytetracycline to affect the synthesis of protein, RNA and DNA in the mycelium of the lincomycin-producing organism Act. roseolus of various ages was studied. The ability of labeled lincomycin to penetrate into the mycelium from the environment was shown and possible presence of the enzymatic systems inactivating lincomycin in the mycelium was studied.

[Pharmacokinetic study of rifampicin in the body of pregnant animals].

The study on distribution of 14C-rifampicin administered intramuscularly to pregnent animals showed that its concentrations in the blood, liver, kidneys, lungs and other organs did not practically change from those in nonpregnant animals. The concentration of 14C-rifampicin in the fetus organs was much lower than that in the organs of the adult animals. The liver and kidneys of the pregnant animals, as well as the fetus though to a less extent had a capacity for metabolism of 14C-rifampicin.

[Pharmacokinetics and biotransformation of rifamycins in the body of experimental animals].

The study on distribution of 14C-rifampicin and 14C-rifamycin S in experimental animals after intramuscular administration of the drugs showed that concentrations of rifampicin in the organs and blood were higher than those of rifamycin S. Biotransformation products of both antibiotics, such as 25-deacetylrifampicin, N-oxide of rifampicin, 3-phormylrifamycin SV, rifamycin SV and others were found in the liver, kidneys, bile and urine. No products of the antibiotic metabolism were found in the blood, lungs and spleen.

[Biosynthesis of the labelled rifamycin B in the presence of different 14C- and 3H-precursors].

The results of studying the effectiveness of incorporation of the label from different 14C- and 3H-precursors into the molecule of rifamicin B during its biosynthesis are presented. The regularities of the label incorporation into the antibiotic composition as dependent on the time of the precursor addition were investigated. A radiochemically pure preparation of 14C-rifamicin B with specific radioactivity of 3 mcurie/mg was obtained.

[Study of the mechanism of action of minocycline and of certain other tetracycline group compounds].

It was shown that the mechanism of action of minocycline on intact cells of E. coli was similar to that of oxytetracycline, i.e.

[Tetracycline resistance and cell-free systems of protein and polypeptide synthesis].

Acellular systems of synthesis of polyphenylalanin containing the supernatant fraction from E. coli B and ribosomes from an oxytetracycline sensitive strain of E. coli and strains resistant to that antibiotic were almost equally sensitive to oxytetracycline.

[Oxytetracycline binding to E. coli ribosomes].

Binding of oxytetracycline to E. coli ribosomes was studied by equilibrium dialysis. The results are consistent with the existence of two classes of binding sites for the antibiotic on ribosomes having different reactivities.