Sarcoidosis of respiratory system at the beginning of the III Millennium

Sarcoidosis of respiratory system is a systemic granulomatosis disease accompanied by the development of epithelioid cell granulomas. During the treatment by glucocorticosteroid drugs or spontaneously, these granulomas disperse or get compacted. Connective tissue with annular distribution is formed around them. Sarcoidosis is etiologically, clinically and morphologically close to tuberculosis. The highest incidence of sarcoidosis has been observed among the urban population of the North of Europe (England, France, Sweden, Poland) - from 20 to 40 per 100000 population. In Russia summary data on the incidence of sarcoidosis does not exist. In the beginning of the Third Millennium according to the St. Petersburg sarcoidosis data it was 8-11 per 100000 people. The basis for justification of the tuberculous nature of sarcoidosis was the similarity of granulomas structure, its combination with tuberculosis and its transformation into tuberculosis with the release of Mycobacterium tuberculosis. The main argument among the opponents of this etiology of the sarcoidosis - is the lack of effect from taking antituberculous medicine. Inefficiency takes place because the point of application of these drugs is the microbial wall. In sarcoidosis, granular and L-forms of mycobacteria with thin cell wall and changes in its structure with which antituberculous drugs contact them are detected in patients. Growth of such microorganisms on special nutrient media causes the restoration of the structure of microbial wall with the restoration of the bacteriostatic effect of anti-tuberculosis drugs.

An ultrastructural study of the late-blight fungus Phytophthora infestans and its interaction with the foliage of two potato cultivars possessing different levels of general (field) resistance

In the susceptible reaction of foliage of the cultivar Majestic there was extensive colonization of the host tissue prior to the onset of necrosis. The development of intracellular hyphae was confined to the initially parasitized palisade cells. Thereafter the fungus grew as intercellular hyphae, which penetrated host cells and formed haustoria. Haustorial morphology was highly variable, ranging in type from small spherical to much larger digitlike structures. Haustorial formation was preceded by the laying down of a moderately electron-dense penetration matrix bounded by the host plasmalemma. This material probably constituted the extrahaustorial matrix once haustorial development had taken place. The matrical material stained with silver proteinate reagent, and this reaction was blocked by dimedone, indicating that it was carbohydrate in nature. In the resistant reaction of foliage of the cultivar Shamrock, the epidermal cells rapidly became necrotic. Quantities of exceedingly electron-dense granules appeared in the necrotic host cells. Host organelles were no longer recognizable, but the fungal cytoplasm remained intact. In adjoining host cells, thin cell wall appositions were formed, which had a heterogeneous composition. On occasions when the fungus attempted to invade an underlying mesophyll cell, papillae usually formed in that cell at the site of incipient penetration.

The structure of cellulose-producing bacteria, Acetobacter xylinum and Acetobacter acetigenus

The structure of the pellicles and cells of the cellulose-producing bacteria, Acetobacter xylinum and Acetobacter acetigenus, was studied by transmission electron microscopy of thin sections and freeze-etch replicas of glucose-stimulated cell suspensions, quiescent cell suspensions, and discrete pellicles. These bacteria have a relatively thin cell wall in section, with several irregular features superimposed on an otherwise simple, Gram-negative morphology. There are no flagella or pili. Unfixed, unextracted cells, viewed as whole mounts, show spherical or ellipsoidal bodies of undetermined composition which disappear after extraction with water or ethanol and propylene oxide. For both species, there are several kinds of cell surface irregularities, some of which are localized protrusions of the cell envelope. A variety of irregularities is seen frequently on cells in the first minutes of glucose incubation, on cells in a discrete pellicle, on quiescent cells, and on starved cells. Immediately after the addition of glucose to cellulose-free cells in suspension culture, fine fibrils appear on and (or) near the cell envelope. The fine fibrils are frequently as small as 3 nm in diameter in both freeze-etch and thin-section preparations and are frequently associated with freshly synthesized cellulose fibrils. Starved cells in suspensions free of (classical) microfibrils sometimes reveal stubs of an extracellular structure whose morphology resembles that of a nascent cellulose fibril.

Association of a small coryneform bacterium with the ratoon stunting disease of sugar-cane

When fibrovascular sap extracts of sugar-cane plants affected by the ratoon stunting disease (RSD) were centrifuged and the resuspended pellets negatively stained and examined in an electron microscope, cells of a small bacterium were always observed. The bacterium could be distinguished readily from other bacteria present by its small size (usually 1.0–2.5 µm long by 0.15–0.32 µm wide), the coryneform (club-shaped) morphology of some cells, and its permeability to negative stain revealing a thin cell wall surrounding a cytoplasmic membrane and coiled mesosomes. Since the small bacterium was never observed in fibrovascular extracts of RSD-free sugar-cane plants, it is a possible causal agent of RSD.

THE CELL WALL AND CELL DIVISION OF GRAM-NEGATIVE BACTERIA

The cell wall of Gram-negative bacteria is generally complex and multilayered. Many, exemplified by Escherichia coli and Spirillum serpens in this study, show a constrictive division in which die cell appears to be pinched in the middle and septa are not seen. It was found that sections of E. coli and S. serpens show true septum formation in a high proportion of dividing cells when they were grown and fixed at 45°. Cells grown at 45° still showed some septum formation if cooled to 20° before fixation. However, septa were demonstrated in cells grown and fixed at 30° when the buffer used in the Ryter and Kellenberger fixative was diluted 1:6; it would appear that the tonicity of the fixing environment is critical. These septa involve an annular invagination of the plasma membrane and the concomitant synthesis of an extremely thin cell wall septum, which appears to consist of the mucopeptide layer alone. Centripetal splitting of this layer and synthesis of the outer layers of the wall follow but are sufficiently delayed that a complete septum was often visible. This form of septum has been known as the normal habit fur some and can now be considered normal for most, if not all, Gram-negative bacteria. The reason for the appearance of constriction in dividing cells fixed by commonly accepted methods remains obscure but attention is drawn to the problems of artefact in the preservation and study of dynamic structures at high resolution.