[Antimicrobial activity of core-sheath surgical sutures modified with poly-3-hydroxybutyrate].

To impart antimicrobial activity to surgical sutures, weaved polyester fibers are coated with poly-3-hydroxybutyrate (PHB), containing the antimicrobial agent furazolidone (FZ). The prolonged FZ effect (7-14 days) is achieved by two-step application of a sheath, constituting 10% of the suture weight and containing 2-6% FZ. The sheath structure and antimicrobial activity of sutures can be modified by the introduction of other biocompatible and biodegradable polymers.

[Ultrastructure of resting cells of some non-spore-forming bacteria]. / Tonkoe stroenie pokoiashchikhsia kletok nekotorykh nesporoobrazuiushchikh bakterii.

Using electron microscopy (ultrathin sections and freeze-fractures), we investigated the ultrastructure of the resting cells formed in the cultures of Micrococcus luteus, Arthrobacter globiformis, and Pseudomonas aurantiaca under conditions of prolonged incubation (up to 9 months). These resting cells included cyst-like forms that were characterized by complex cell structure and the following ultrastructural properties: (i) a thickened or multiprofiled cell wall (CW), typically made up of a layer of the preexisting CW and one to three de novo synthesized murein layers; (ii) a thick, structurally differentiated capsule; (iii) presence of large intramembrane particles (d = 180-270 A), occurring both on the PF and EF sides of the membrane fractures of M. luteus and A. globiformis; (iv) a peculiar structure of the cytoplasm, which was either fine-grained or lumpy (coarse-grained) in different parts of the cell population; and (v) a condensed nucleoid. Intense formation of cyst-like cells occurred in aged (2- to 9-month-old) bacterial cultures grown on diluted complex media or on nitrogen-, carbon-, and phosphorus-limited synthetic media, as well as in suspensions of cells incubated in media with sodium silicate. The general morphological properties, ultrastructural organization, and physiological features of cyst-like cells formed during the developmental cycle suggest that constitutive dormancy is characteristic of non-spore-forming bacteria.

[Changes in the fine structure of microbial cells induced by chaotropic salts]. / Izmenenie tonkoi struktury kletok mikroorganizmov pod vozgeistviem solei-khaotropov.

The electron microscopic examination of the thin sections of cells of the yeasts Saccharomyces cerevisiae and Pichia pastoris and the gram-positive bacteria Micrococcus luteus and Bacillus subtilis showed that cell treatment with the chaotropic salts guanidine hydrochloride (6 M) and guanidine thiocyanate (4 M) at 37 degrees C for 3-5 h or at 100 degrees C for 5-6 min induced degradative processes, which affected almost all cellular structures. The cell wall, however, retained its ultrastructure, integrity, and rigidity, due to which the morphology of cells treated with the chaotropic salts did not change. High-molecular-weight DNA was localized in a new cell compartment, ectoplasm (a peripheral hydrophilic zone). The chaotropic salts destroyed the outer and inner membranes and partially degraded the outer and inner protein coats of Bacillus subtilis spores, leaving their cortex (the murein layer) unchanged. The spore core became accessible to stains and showed the presence of regions with high and low electron densities. The conditions of cell treatment with the chaotropic salts were chosen to provide for efficient in situ PCR analysis of the 16S and 18S rRNA genes with the use of oligonucleotide primers.