Induced variability of Streptomyces galbus

A-factor, a regulating substance is an obligatory participant of streptomycin biosynthesis by Str. griseus. Str. galbus also synthesizes streptomycin but without participation of A-factor. Mutant with various morphological properties were obtained under the effect of ethylenimine. No correlation between spore formation and streptomycin synthesis was found in the mutants of Str. galbus unlike Str. griseus. Correlation between a decrease in the capacity for production of a dark brown pigment and an increase in the level of streptomycin biosynthesis was shown: the mutants with the dark brown pigment did not synthesize streptomycin, while the mutants without the pigment synthesized streptomycin in the amounts 10-14 times higher than those in the initial strain. The same as the initial strain, the mutants of Str. galbus had no A-factor and did not respond to its addition into the medium by changing their properties and streptomycin synthesis.     

The genetic characteristics of the analgesic action of substance P, bradykinin and thyroliberin in the rats of 2 inbred strains

A participation of nonopiate peptide brain systems in the mechanism of individual pain sensation was studied. The experiments were carried out on rats of two inbred strains, Fischer-344 and WAG/G, which exhibit different threshold of thermal pain sensation. The action of nonopiate oligopeptides (substance P, bradykinin, and thiroliberin) on the latent period of tail immersion from hot water was studied. It was found that significant analgesic action of substance P, bradykinin, and thiroliberin is more pronounced in rats more sensitive to thermal stimuli (WAG/G). The rats with reduced thermal sensitivity (Fischer-344) are shown to be insensitive to analgesic action of substance P, bradykinin, and thiroliberin.     

Spontaneous liposome formation induced by grafted poly(ethylene oxide) layers: theoretical prediction and experimental verification

Spontaneous liposome formation is predicted in binary mixtures of fluid phase phospholipids and poly(n)ethylene oxide (PEO)-bearing lipids by using single chain mean field theory. The range of stability of the spontaneous liposomes is determined as a function of percentage of PEO-conjugated lipids and polymer molecular weight. These predictions were tested by using cast films of 1, 2-diacyl-sn-glycerophosphocholines (e.g., egg L-alpha-lecithin, 1, 2-dimyristoyl-sn-glycero-3-phosphocholine, 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine, and 1, 2-distearoyl-sn-glycero-3-phosphocholine) and 1, 2-dipalmitoyl-sn-glycerophosphatidylethanolamine-PEO conjugates (i.e. , 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxypoly(e thylen e glycol)2000]carboxamide and 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxypoly(e thylen e oxide)5000]carboxamide) that were hydrated above their gel-liquid crystal phase transition temperatures. Particle sizes of the resulting dispersions, analyzed by quasielastic light scattering, solute retention, 31P NMR, and freeze-fracture electron microscopy measurements, confirmed the single chain mean field predictions. These data indicate that thermodynamically stable, unilamellar liposomes are formed spontaneously by simple hydration of fluid phase phospholipid bilayer films containing low molar ratios of PEO-based amphiphiles. They further suggest that the equilibrium size and colloidal properties of fluid phase, PEO-modified liposomes can be predicted by using this theoretical approach. The implication of these results on the design and processing of sterically stabilized liposomes used in drug delivery applications also is described.     

Etiology, pathogenesis and treatment of severe recurrent forms of erysipelas of the lower extremities

The experience of treatment of 314 patients with erysipelas was summarized. The organizational principles of struggle against this disease are proposed.     

New site-specific endonucleases from strains of Bacillus

In a search for new restriction endonucleases type II, among forty bacterial strains of the Bacillus genus two strains producing site-specific endonucleases have been found. Endonucleases BbvAIII and BspFI, isolated from B. brevis BLM B-677 and B. species F, are shown to be true isoschisomers of BspMII (Kpn2I) and Sau3AI, respectively.     

Calcium uptake via endocytosis with rapid release from acidifying endosomes

A number of specific cellular Ca2+ uptake pathways have been described in many different cell types [1] [2] [3]. The possibility that substantial quantities of Ca2+ could be imported via endocytosis has essentially been ignored, although it has been recognized that endosomes can store Ca2+ [4] [5]. Exocrine cells can release significant amounts of Ca2+ via exocytosis [6], so we have investigated the fate of Ca2+ taken up via endocytosis into endosomes. Ca2+-sensitive and H+-sensitive fluorescent probes were placed in the extracellular solution and subsequently taken up into fibroblasts by endocytosis. Confocal microscopy was used to assess the distribution of fluorescence intensity. Ca2+ taken up by endocytosis was lost from the endosomes within a few minutes, over the same period as endosomal acidification took place. The acidification was inhibited by reducing the extracellular Ca2+ concentration, and Ca2+ loss from the endosomes was blocked by bafilomycin (100 nM), a specific inhibitor of the vacuolar proton ATPase. Quantitative evaluation indicated that endocytosis causes substantial import of Ca2+ because of rapid loss from early endosomes.     

Adaptive response in vivo: reasons for increase of radioresistance in CFU-S

The data concerning the reasons of CFU-S radioresistance increase after low dose irradiation of mice were obtained; the reparation processes in CFU-S adapted by low dose irradiation were shown to be more active than in intact ones. Colony formation increase was demonstrated to be more pronounced in adapted animals when they had been injected by 50 mcg of synthetic polyribonucleotide PolyI-PolyC two days before irradiation in challenge dose. The thymogen immunomodulator administration to adapted and intact donor animals leads to the increase of colony yield in equal extent.