[Electron microscopy of the surfaces of bacillary spores].

The surface structures of the spores of Bacillus. cereus, B. thuringiensis, and Brevibacillus laterosporus were studied by transmission and scanning electron microscopy. Platinum deposition and negative staining with uranyl acetate revealed appendages and exosporium in B. thuringiensis and B. cereus. The exosporium structure was visualized by negative staining and ultrathin sectioning. For staining the exosporium polysaccharide, Alcian blue was used during fixation. The results obtained show the differences in structural organization of appendages and exosporium in different strains. Canoe-shaped inclusions were revealed in all Br. laterosporus strains, while strain IGM16-92 had a fibrillar capsule as well. Electron microscopy using a dual beam scanning electron microscope Quanta 200 3D provided the information of the spore surface relief without sample treatment (fixation and dehydration). The spores of Br. laterosporus strains had folded surface, unlike the smooth surface of B. cereus and B. thuringiensis spores. Diversity of external spore structures was shown within a species, which may be used for detection of bacteria at the strain level. Optimized procedures for visualization of spore surface by different electron microscopic techniques were discussed.

[Structural changes of the adrenal cortex in experimental genital herpes virus infection].

The reactive changes in the adrenal gland cortex were studied in mature female guinea pigs (n=5) in an experimental model of acute genital herpes virus infection. The methods of light and transmission electron microscopy were used. To confirm the presence of viral antigen in the corticosterocytes (CSC), the methods of immunfluorescence and electron microscopic immunocytochemistry were used. It was shown that at day 7 of an acute process, focal CSC reactive changes appeared in the glomerular zone - at the light microscopic level, CSC had intact nuclei and optically empty cytoplasm, while at the electron microscopic level, these CSC demonstrated the damaged membranous organelles, and various membranous structures which were not found in the normal cells. The aggregates of hypertrophied CSC were found in the fasciculate zone. The changes described were reversible, as they practically disappeared by the onset of spontaneous recovery (day 21 after inoculation). The regeneration of CSC of glomerular and fasciculate zones of the adrenal cortex involves both intracellular and cellular mechanisms.

[Infectious genesis of nephroliths (electron-microscopic study)].

Scanning electron microscopy and x-ray microstructural analysis were employed in the study of nephroliths from patients suffering from nephrolithiasis. Bacterial biofilms, urease producing microorganisms, alkaline reaction of the urine are basic factors for local urine crystallization, formation of the base of the nephroliths and its rigid fixation to the pelvic mucosa. Mechanic trauma of the pelvic tissues by the concrement results in destruction of the pelvic mucosa epithelium at the site of the nephrolith. Subsequent inflammation in the underlying connective tissue contributes to formation of connective tissue commissures fixing the conrement in the kidney. It is shown that bacteria as a part of a biofilm are capable to persist in nephroliths for a long time. Destruction of the stones during operation or lithotripsy can trigger activation of growth of bacteria integrated in the biofilm and cause septic complications. Preservation of commissures with elements of the destroyed stone after lithotripsy or surgical removal is one of the leading causes of recurrent nephrolithiasis.

[Renal calculus microflora in urolithiasis and search for agents of control of biofilms formed by uropathogenic bacteria].

AIM: Study bacterial biofilms in native material (renal calculus) by electron microscopy method and developmeit of biofilm model by isolates in vitro on sterile calculi of various chemical composition. MATERIALS AND METHODS: Bacterial spectra of microflora of renal calculus lavages were studied, isolated pure cultures were identified up to species. Comparisons of urine microflora obtained before operation in patients with urolithiasis with microflora of removed renal calculi were carried out. RESULTS: Urease activity and genes coding pathogenicity factors were detected, and the ability to form biofilms by isolates was studied. Model of formation of biofilms in vitro on sterile renal calculi was developed and candidate agents reducing the biofilm forming ability were tested. CONCLUSION: Uropathogenic microorganisms infecting renal calculi and forming biofilms on them not only support chronic infection by increased resistance to therapy but also facilitate novel lithogenesis.

[Intraovarian regulators of folliculogenesis].

The review summarizes information about the intraovarian modulators of folliculogenesis. Consistently described auto-and paracrine factors and mechanisms involved in the regulation of follicular development from the entry in the growth of primordial follicles before ovulation of the dominant follicle.

[Persistence of Burkholderia cenocepacia bacteria in vivo in dependence of their ability to form biofilms].

AIM: To select the most susceptible line of mice which allows to conduct comparative studies of infectious process caused by different strains of B. cepacia in order to explore correlation between ability to form biofilms and persistence of bacteria in organs of infected animals. MATERIALS AND METHODS: Strain B. cenocepacia 370, which is a clinical isolate, and its mutants with modified ability to form biofilms were used. Conditional microbiologic methods and biological models of intraperitoneal and intranasal inoculation of mice belonging to 4 lines: BALB/c, BLACK, I/St, and A/Sn derived in Central Institute of Tuberculosis were employed. Criteria of persistence was duration of isolation of different strains of bacteria from lungs and spleen of inoculated animals as well as number of CFU. RESULTS: The most susceptible line of mice which enables to conduct comparative studies of infectious process caused by Burkholderia species was determined. It was shown that even after intraperitoneal inoculation the agent was better preserved in lungs than in spleen that corresponds to natural localization of this infection. At any time of observation the number of cells of mutant strain, which is a superproducer of biofilms, isolated from organs of inoculated mice was 2 - 10 times higher than number of isolated cells of mutant, which do not produce biofilms. CONCLUSION: Correlation of more prolonged persistence of B. cenocepacia in organs of inoculated animals in vivo with ability of the agent to form biofilms determined in vitro is experimentally established. The susceptible line of mice which allows to conduct comparative studies of dynamics of infectious process caused by various strains of Burkholderia species was revealed. It was shown that irrespective from method of inoculation B. cepacia are able to continuously persist in organism of susceptible animals with lungs as a predominant localization.

[Study of persistence of low virulent strain of Toxoplasma gondii on in vivo model].

AIM: To study virulence of Toxoplasma gondii strain isolated from pathologicoanatomic brain tissue of HIV-infected patients on in vivo model as well as immune response to the pathogen in immunocompetent animals and in animals with cyclophosphamide-induced areactivity. MATERIALS AND METHODS: Groups of immunocompetent and immunodeficient mice were inoculated with cysts of T. gondii obtained from brain tissues of deceased HIV-infected patients. Parasites were detected in different organs and tissues by PCR as well as by parasitological and histological methods. Antibodies to T. gondii belonging to isotypes IgG, IgG1, IgG2, IgA were detected by immunofluorescence assay. RESULTS: Cysts of the pathogen located predominantly in animals' brain, and more rarely - in spleen and liver. Using detection of antibodies of different isotypes, which marked stage of invasion, dynamics of humoral response during persistence of toxoplasms in organism was determined. Analysis of disease pathogenesis as well as peculiarities of immune response to the pathogen in immunocompetent animals and in animals with cyclophosphamide-induced areactivity was performed. CONCLUSION: Characteristics of strains of toxoplasms isolated from material of brain section of patients with HIV infection were studied. Their low virulence and ability to prolonged persistence in organism of mice were demonstrated on in vivo model. Possible association of T. gondii strains' virulence and clinical symptoms with pathogen's genetic polymorphism and its clonal population structure was discussed.