[Dissociation and ultrastructure of the cells of Shigella sonnei isolated from gnotobiotes and obtained in vitro]. / Dissotsiatsiia i ul'trastruktura kletok Shigella sonnei, vydelennykh ot gnotobiontov i poluchennykh in vitro.

The dissociation variants of S. sonnei in phase I, isolated from germ-free rats and obtained in vitro, have been studied. Such dissociation variants have been found to form colonies with classical and atypical morphology. The electronmicroscopic study has revealed that different dissociation variants include small dense cells with the markedly thickened cell wall and pronounced microcapsule and spheroplasts with the damaged cell wall and less pronounced microcapsule. The formation of these cells is supposed to be the way of the adaptation of S. sonnei in the course of the infectious process and linked with changes in their virulence in the population cycle.

[Identification of 5-aminovaleric acid as a characteristic product of metabolism of various Clostridium species]. / Identifikatsiia 5-aminovalerianovoi kisloty kak kharakteristicheskogoprodukta metabolizma nekotorykh predstavitelei roda klostridii.

An unusual ninhydrin-positive compound has been isolated from feces of accidentally contaminated Sprague-Dawley autbred rats and identified by mass spectrometry and 1H-NMR spectroscopy techniques as 5-aminovaleric acid. The described procedure of isolation, purification and structure determination can be recommended as a general method of identification of unusual ninhydrin-positive compounds in complex mixtures of biological origin. The 5-aminovaleric acid was found to be produced by an anaerobic bacterium Clostridium bifermentans. It is shown that not all Clostridium spp. excrete his amino acid and that the majority of microorganisms, normally inhabiting intestine of rats, simians and man, do not possess this ability. On the basis of data obtained, the test for 5-aminovaleric acid is proposed to be included into the taxonomy of bacteria.

[Gnotobiology of the host microflora and antibiotic therapy]. / Gnotobiologiia o mikroflore organizma khoziaina i antibiotikoterapii.

Gnotobiological studies showed that under natural conditions normal microflora (microsymbiocenosis) is necessary for normal vital activity. In addition to autochthonous flora microsymbiocenosis includes an insignificant number of facultative pathogenic bacteria. In etiotropic antibiotic therapy it is important to preserve the autochthonous portion of the microsymbiocenonosis: bifidobacteria, lactobacilli, propionic bacteria and others. However, with respect to certain indications (diseases associated with suppression of resistance to infections) total decontamination with obligatory isolation of the patient under gnotobiological conditions is possible. In selective decontamination the facultative pathogenic portion of the intestinal microflora is the sole target of antibiotics. Selective decontamination is one of the methods for control of nosocomial infections, dysbacteriosis. It is indicated that establishment of departments in charge of investigation of intestinal microflora of patients and medical staff in hospitals is required for detecting risk groups which can be both the source of infection and the population most susceptible to hospital strains of antibiotic resistant facultative pathogenic bacteria.

[The adhesive capacity of representative intestinal microflora in the continuous and split oral administration of cephalexin and erythromycin]. / Adgezivnaia sposobnost' predstavitelei kishechnoi mikroflory pri nepreryvnom i drobnom oral'nom vvedenii tsefaleksina i éritromitsina.

When cephalexin and erythromycin were administered intragastrically with intervals, adhesion of facultative pathogenic bacteria such as Klebsiella, Staphylococcus and E. coli to enterocytes of the small intestine in vitro was more pronounced than with their continuous administration with drinking water. The adhesive capacity of the staphylococcal strains resistant to the antibiotics was higher than that of the sensitive ones.

[Changes in the microflora of the large intestine in rats administered cephalexin and erythromycin orally]. / Izmenenie mikroflory tolstoi kishki krys pri oral'nom vvedenii tsefaleksina i éritromitsina.

The effect of long-term use of cephalexin and erythromycin (for 17 days) on large intestine microflora was studied on rats. It was found that intragastric administration of cephalexin in a dose of 800 mg/kg and erythromycin in a dose of 400 mg/kg was followed by changes in the quantitative and qualitative composition of the large intestine aerobic and anaerobic microflora. However, it did not induce production of beta-aspartyl glycine which is a biochemical indicator of deep changes in intestinal microflora. The long-term use of the above antibiotics resulted in increased levels and persistence of intestine colonization with facultative pathogenic enterobacteria and staphylococci resistant to the chemotherapeutic agents.

Gnotobiological research of the host-microflora interaction.

The last two decades indicate that one of the main features of modern gnotobiology are comparative experiments on germfree and conventional counterparts to study the significance of normal (or dysbiotic) microflora (or individual species) in various physiological and pathological processes of the host organism. There are some immunological consequences of absence of normal microflora. Interactions between some indigenous and pathogenic bacteria in the intestine of gnotobiotic and conventional rats are discussed.

[Phenomenology and molecular mechanisms of Shigella sonnei dissociation: its variability in model in vivo and in vitro systems]. / Fenomenologiia i molekuliarnye mekhanizmy dissotsiatsii Shigella sonnei: izmenchivost' v model'nykh sistemakh in vivo i in vitro.

The dynamics of the accumulation of phase II S. sonnei in the infectious process in germ-free rats, during cultivation and in subcultures was studied. The in vivo variability of S. sonnei showed a sharply defined phasic character of the process with the periods of the apparent absence of phase II, the increase of its occurrence and stabilization with the preservation of S-forms in minor amounts. Kanamycin-resistant phase II accumulated in vivo more rapidly than in vitro. Cultivation with sodium desoxycholate was found to accelerate the process of disassociation. The characteristic feature of all dissociants detected in all systems was their plasmid profile: in phase I, plasmids of 120 and 60 Md, as well as small plasmids, were detected; in phase II disassociants, plasmid with a molecular weight of 120 Md was absent. The restriction analysis of total plasmid DNA by means of restrictase EcoR1 showed the absence of 3 fragments in phase II while other 13 fragments were retained. These results open prospects for the molecular cloning of the gene antigen of phase II.

[Rapid diagnosis of dysbacteriosis by detecting beta-aspartylglycine in the feces in an experiment]. / Ekspressnaia diagnostika disbakterioza putem obnaruzheniia beta-aspartil-glitsina v fekaliiakh v éksperimente.

In experiments on Fischer rats (F-344), both with common microflora and germ-free, the influence of the systemic destination of different antibiotics (tetracycline + ampicillin, gentamicin + kefzol, gentamicin, fradizine) on the intestinal microflora, the content of beta-ospartylglycine in feces and the colonization resistance of the intestinal tract to Staphylococcus aureus B-243 and Pseudomonas aeruginosa No. 93 has been studied. The early appearance of beta-aspartyl-glycine in the supernatant of fecal samples has been shown to be the first sign of dysbacteriosis and to indicate the decrease of the colonization resistance of the intestine to opportunistic bacteria.

[Interrelation of virulent and avirulent (vaccinal) strains of Shigella flexneri 2A in long-term bacterial carriage in gnotobiotic rats]. / Vzaimootnosheniia virulentnogo i avirulentnogo (vaktsinnogo) shtammov Shigella flexneri 2A pri dlitel'nom bakterionositel'stve u krys-gnotobiontov.

The ability of S. flexneri 2a virulent and avirulent (vaccine) strains No. 516 and No. 516 m to displace one another during long-term carrier state in germ-free rats has been studied. The long-term persistence of the vaccine strain in the intestine of the rats has been shown to produce colonization resistance to subsequent infection with the virulent culture of these bacteria. During carrier state in rats progressive S--R dissociation of the bacteria occurs, type II antigen is lost with simultaneous retention of group 3, 4 antigens and the resulting transformation of S. flexneri, serotype 2a, into variant y; the virulence of Shigella S-forms is also lost.

[Adaptation of the antibiotic-resistant bifidobacteria in the intestines of normal and pathogen-free animals]. / Izuchenie prizhivleniia antibiotikoustoichivykh bifidobakterii v kishechnike obychnykh i steril'nykh zhivotnykh.

Antibiotic-resistant bifidobacteria have the ability to actively interact with mucosal tissue from the intestine of mice and rats in vitro and to adapt well in the intestinal tract of normal and germ-free rats, when introduced both with and without antibiotics; in some cases antibiotics enhance the ability of bifidobacteria to adapt in the intestine. The interaction between antibiotic-resistant bifidobacteria and mucosal tissue from the intestine remains unaffected by the prolonged action of 0.1M SDS and Tween-80 solutions, 0.1% trypsin and hyaluronidase. Antibiotic-resistant bifidobacteria introduced into the intestinal tract of rats in combination with gentamycin effectively inhibit the multiplication of exogenous enterobacteria infecting the digestive tract after the cessation of the antibiotic administration.

[Intestinal mucosa of gnotobiotic rats administered lactobacilli]. / Slizistaia obolochka kishki krys-gnotobiontov pri vvedenii laktobatsill.

When lactobacilli are administered to gnotobiotic rats (Fischer strain), a gradual increase of lymphocytic, eosinophilic and mast cell infiltration of the intestinal connective tissue stroma, dilatation of vessels and their filling with lymphocytes is observed. Radioautographically 7 months later, migration and differentiation of enterocytes in the crypta--villus system of the iliac mucous tunic increases. In the mesenteric lymph nodes the postcapillary venules increase in number, lymphocytes migrate out of them, focal plasmocytic reaction with presence of some blastic forms takes place. Specific antibodies for lactobacilli in the blood serum either are absent or occur in low titers (1:2-1:8). Owing to the data obtained, a conclusion can be made on a weak immunogenecity of the lactobacilli. Their administration to the germ-free rats produces a certain cellular reaction, probably T-dependent, though any definite signs of hormonal response are absent. One--14 days after lactobacilli have been injected, in the rat intestine mucous tunic no microorganisms are revealed to fix to enterocytes. In cytoplasm of the absorbtive cell villi, the Golgi complex is subjected to hyperplasia and occupies an essential area over the nucleus. Within its cysterns, as well as in the mitochondrial and nuclear membrane areas, myelin-like bodies are revealed; evidently, they demonstrate certain changes in peroxidic oxidation of lipids..

[Latent bacterial carrier state and resistance to colonization after antibiotic therapy]. / Skrytoe bakterionositel'stvo i kolonizatsionnaia rezistentnost' posle antibiotikoterapii.

The enteral administration of antibiotics has been shown to induce the occult carriership (persistence) of sporulating Gram-positive bacilli inhabiting the intestine before the use of antibiotics and V. eltor introduced orally after the administration of antibiotics is stopped. After the prolonged use of some antibiotics the intestinal tract has been found to become an inadequate environment for the life of nonpathogenic E. coli easily colonizing the intestine of intact germ-free animals. Such form of resistance of colonization is an unfavorable consequence of antibiotic therapy.

[Ultrastructure of the small intestine mucosa of gnotobiotic rats with a Vibrio cholerae carrier state]. / Ul'trastruktura slizistoi obolochki tonkoi kishki krys-gnotobiontov pri kholernom vibrionositel'stve.

Ultrastructure of the small intestinal mucosa of gnotobiotic rats, carriers of Vibrio eltor or V. Cholerae was studied. The cytoplasm of enterocytes manifested an increased number of lysosome-like structures and hypertrophy of the Golgi complex. Unlike V. eltor, V. cholerae induced more intensive extrusion of enterocytes and appreciable infiltration of the epithelial layer with lymphocytes. It is concluded that chronic vibrio-carrier state in gnotobiotic rats is not associated with pathological alterations.

[Delayed hypersensitivity in the chronic cholera vibrio carrier state in animals with an absence of normal microflora]. / Giperchuvstvitel'nost' zamedlennogo tipa pri khronicheskom kholernom vibriononositel'stve u zhivotnykh s otsutstviem normal'noi mikroflory.

The development of allergy in germ-free rats in chronic vibriocarriership was studied. The formation of specific delayed type hypersensitivity was found to occur to a limited extent in the animals devoid of normal microflora. The picture of hyperergic inflammation was revealed in the lymph nodes of vibriocarrier rats, the test for specific allergen being positive.

[Structural characteristics of the mucosa of the small intestine in gnotobiote rats]. / Strukturnye osobennosti slizistoi obolochki tonkoi kishki u krys-gnotobiontov.

Histological and electron microscopic investigations of mucosal strucutre of the small intestine in gnotobiotic and conventional rats have demonstrated that mucosal index (lenear dimentions of villi/crypt dimentions ratio) is equal to 3--4 and 1.4--2.5, respectively. In gnotobiotic rats the number of mitotic figures in crypts is less, migratory-desquamative parameters of enterocytes are 5--6 days, cranio-caudal gradient of linear dimentions of villi, crypts and the number of goblet-shaped cells is not expressed. The goblet-shaped cells and cells with acidophilic granules have secretion of moderate intensity. The number of cells infiltrating epithelium of villi and crypts is greater when microbes are present in the gut lumen. A considerable difference in the structure of the connective tissue basis of the gnotobiotic and conventional rats mucosa are also connected with presence or absence of microflora in the gut lumen.

[Action of cyclophosphane on the formation of hemagglutinins and of nonspecific immunoglobulins in a microbe-free state]. / Deistvie tsiklofosfana na obrazovanie gemaggliutininov i nespetsificheskikh immunoglobulinov pri stause bezmikrobnosti.

A total of 39 germ-free and 28 conventional germ-free Fisher rats were used to study cyclophosphamide-induced specific (hemagglutinins) and nonspecific (IgG2) immunosuppression. Most pronounced effect of the drug was observed in germ-free animals. 180 mg/kg of cyclophosphamide completely suppressed hemagglutinin formation for at least 8 weeks.