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Biomedical subjects

A Umeda

Publications and source records attributed to A Umeda.

At least 91 records · Page 5Linked to original sources
PubMed1986

Structural changes in the nucleoid of Bacillus subtilis at low temperature.

The external shape of the nucleoid of Bacillus subtilis strain w23 was examined with a new electron microscopic technique, the rapid freezing and substitution fixation method. The nucleoid of the log and stationary phase cells was recognized as an area devoid of ribosomes and widely dispersed in the cytoplasm, which was different from that observed in OsO4-fixed cells. If the bacteria were exposed to low temperatures (0 to 10 C), the nucleoid showed a highly concentrated shape in the middle of the cytoplasm. These structural changes were observed only when the bacteria were maintained in a high-salt buffer. The results are discussed in relation to the membrane fluidity at low temperature.

Bacillus subtilis↗
PubMed1986

Astromicin-induced membrane damage in Serratia marcescens.

The morphological changes in Serratia marcescens induced by astromicin were determined by a new technique of electron microscopy, a rapid freezing and substitution fixation technique, and a freeze-fracturing technique. Two structural changes were observed. One was damage to the cytoplasmic membrane, and the other was the accumulation of a large electron-dense mass in the cytoplasm. The damage observed in the cytoplasmic membrane was the disappearance of the unit membrane structure from the thin-sectioned profile of the drug-treated bacteria and the loss of the membrane particles from the fractured surface of the membrane. Damage to the membrane was also suggested by the results of examination of the spheroplasts for stability. The spheroplasts prepared from the drug-treated bacteria were unstable in an osmotically controlled buffer. Most of the spheroplasts were lysed within 3 h, whereas those prepared from control cells were stable for more than 15 h. The electron-dense mass in the cytoplasm was usually seen in the polar region of the cell in close contact with the cell membrane. These structural changes were not specific for astromicin but were also found in gentamicin-treated cells.

Aminoglycosides↗
PubMed1985

Motility as an intestinal colonization factor for Campylobacter jejuni.

The colonization of the intestinal tract of suckling mice by Campylobacter jejuni was examined by orally challenging the mice with a wild-type strain and several nonmotile mutant strains which were isolated after treating the wild-type strain with mutagens. The wild-type strain had colonized the lower portion of the small intestine, the caecum and the colon 2 d after inoculation. Two nonmotile strains, one of which (M8) had lost all the flagellar structure including the filament, the hook and the basal structure, and the other (M1) which had lost only the filament region, were both cleared from the intestinal tract 2 d after challenge. Another nonmotile strain (M14), which had a complete flagellar structure like that of the wild-type strain, did not colonize and was cleared from the intestinal tract like the other nonmotile and nonflagellated strains. One atypically motile strain (M5), which had a shorter flagellar filament than that of the wild-type strain, colonized the intestinal tract only when mice were challenged with a large inoculum. None of the mice challenged with either the wild-type or any of the mutant strains showed signs of illness. We concluded that motility is an important factor in the colonization of the intestinal tract of suckling mice by C. jejuni.

Adhesiveness↗
PubMed1984

Cross wall synthesis and the arrangement of the wall polymers in the cell wall of Staphylococcus spp.

The growing process and the fine structure of the cross wall of Staphylococcus were investigated by electron microscopy. Examination of the tangentially sectioned cross wall revealed that it was initially synthesized as a thin cell wall layer by an invaginated cytoplasmic membrane. The wall thickness soon increased by additional synthesis of the wall from the cytoplasmic membrane located at the side region of the cross wall. Scanning electron microscopic observation of sodium dodecyl sulfate-treated and mechanically separated cross walls revealed that the outer surface of the cross wall exhibits regular circular structures and the inner surface showed has an irregular surface. This indicates that cell wall materials were arranged in a regular circular manner in the initially synthesized thin layer. It is conceivable that in Staphylococcus spp. two cell wall synthesizing systems are present: wall-elongation synthesis in which wall materials are arranged in a regular circular manner and wall-thickening synthesis in which wall materials are arranged in an irregular manner.

Cell Wall↗
PubMed1983

Morphological differences in flagella in Campylobacter fetus subsp. intestinalis and C. fetus subsp. jejuni.

Intact flagella were isolated from human pathogenic strains of Campylobacter, C. fetus subsp. intestinalis and C. fetus subsp. jejuni, by the method of DePamphilis and Adler and examined by electron microscopy. The isolated flagella were composed of a filament, a hook, a basal body, and a large disk associated with the end of the hook region covering the basal body. The width of the hook was approximately 28 nm, somewhat greater than that of the filament (20 nm in diameter). The hook region of C. fetus subsp. intestinalis was curved, but it was straight in C. fetus subsp. jejuni. The structure of the basal body of the two subspecies was similar to that reported for other gram-negative bacteria. The large disk detached from the flagella showed concentrically arranged circular structures. This structure was more clearly observed in the disk of C. fetus subsp. jejuni than in C. fetus subsp. intestinalis. Observations of thin-sectioned profiles at the attachment site of the flagellum revealed that the large disk is located on the inner side of the outer membrane. The role of the large disk in bacterial movement is not clear, but it is assumed that it acts as an organ to protect the flagellar insertion site from vigorous rotation of the polar end inflicted during bacterial movement.

Campylobacter fetus↗
PubMed1983

Growth of the surface of Corynebacterium diphtheriae.

Surface structure and growth of the surface of Corynebacterium diphtheriae mitis strain were investigated by scanning electron microscopy and the immunofluorescence technique. The surface of the cell revealed by the scanning electron microscope showed a few elevated circular zones which encompassed the cell. The cell diameter increased at this zone and this gave the club-shaped appearance to this species. The cell surface labeled with specific antibodies against the whole bacterial cell and tagged with ferritin remained at a constant length during cell division cycles and the new cell surface emerged from the polar ends of the cell. This new wall surface was completely devoid of the ferritin particles indicating that the cell wall component on the old preexistent wall was completely conserved. A similar finding was obtained by immunofluorescence microscopy. C. diphtheriae, unlike Bacillus spp., showed apical growth as has been observed in fungal cells.

Cell Division↗
PubMed1982

Arrangement of peptidoglycan in the cell wall of Staphylococcus spp.

The arrangement of peptidoglycan in the cell wall of Staphylococcus was observed with the newly developed freeze-fracture technique, using n-octanol instead of water as the freezing medium. The replica of the trichloroacetic acid-extracted cell wall (TCA-wall) showed two areas. One of them has a concentric circular structure, a characteristic surface structure of the staphylococcal cell wall, and the other showed an irregular and rough surface. The chemical analysis of the wall revealed that the TCA-wall consisted of mostly peptidoglycan. By digesting the TCA-wall with lysozyme, the circular structures were greatly disturbed, and they disappeared after 60 min of treatment. From these observations it can be expected that the peptidoglycan is arranged in a concentric circular manner in the newly generated cell wall of Staphylococcus.

Cell Wall↗
PubMed1980

Localization of bacteriophage receptor, clumping factor, and protein A on the cell surface of Staphylococcus aureus.

The surface of several laboratory strains of Staphylococcus aureus were observed with a scanning electron microscope, and the presence of two morphologically characteristic structures--a ridge separating cell surface into old and new surfaces and a concentric circular structure--are described. These two structures seemed to be present universally on the surfaces of cells of the genus Staphylococcus. The removal of the circular structures by a mild treatment of the cell with trichloroacetic acid suggested that this structure seemed to represent circularly arranged teichoic acid. With experiments using morphologically recognizable markers among three of the cell wall components, clumping factor, phage receptor, and protein A, the clumping factor was proven to be specifically localized on the old surface; and more phage receptors were detected on the old surface than on the new surface, but protein A was present all over the cell surface. This indicated that the clumping factor and most of the phage receptors appeared on the cell wall surface in a late stage of the cell growth cycle, but protein A was present in an early stage of the growth. The idea of aging of the cell wall is discussed.

Agglutinins↗
PubMed1979

Regular arrangement of wall polymers in staphylococci.

Concentric circular structures were observed on the newly exposed surface of the wall of Staphylococcus epidermidis and on its isolated cross-wall. These structures were removed by treatment with trichloroacetic acid. Chemical analysis revealed that after treatment with trichloroacetic acid most of the wall phosphorus was extracted but more than half of the N-acetylglucosamine remained associated with the wall. These observations suggest that polysaccharides are likely to be arranged circularly on the surface of the wall.

Carbohydrate Conformation↗
PubMed1979

Mode of cell separation and arrangement of Staphylococcus.

The process of cell separation and arrangement of Staphylococcus was investigated using a scanning electron microscope. After two cycles of cell division, the Staphylococcal cells cultured on an agar medium were generally observed to be arranged in three morphological types: linear, square, and crooked arrangements. Results of the examination of cell surface structure revealed that separations had occurred in these clustered cells following two patterns. One type of second separation occurred parallel to the transversal axis of the preceding pair of the parental cells (X-type) and the other occurred tangential to it (Y-type). In the former type, the four daughter cells were usually arranged tetragonally after the separations, and in the latter type they were arranged either linearly or crookedly depending on the direction of the second separation. The final pattern of the cell arrangement was thus determined by the type of septal wall formation and the direction of cell separation. After several cycles of cell divisions, the cells were finally arranged in an irregular grape-like cluster, even though the cross walls were formed regularly at the rectangular face of the preceding cross walls.

Cell Division↗
PubMed1979

[Middle cerebral arterial occlusion secondary to brain tumor -- case report (author's transl)].

A thirty-year-old man who had sudden onsets of unconsciousness, right hemiparesis and conjugate deviation to the left side, was admitted to our clinic. The clinical symptoms were similar to an apoplexic attack. The neurologic examination showed right hyperactive knee and ankle reflexes, and left inferior temporal retinal arterial occlusion. The serial left carotid angiography, performed immediately after admission, showed the occlusion of left middle cerebral artery at the location of trifurcation. We diagnosed this case as a cerebral vascular disease, and then the large amount of Urokinase and Heparin were injected immediately after the diagnosis. The clinical symptoms were improved tremendously after the injection. Three days later, the second left carotid angiography showed the complete recanalization of the occlusion, and further did a tumor stain at the distal portion of the occlusion. The brain scintigram revealed an increased up-take of 99mTc in the left parieto-temporal region. We finally diagnosed brain tumor, and the tumor was subtotally removed by the left parieto-temporal craniotomy. The histological findings of the tumor showed angioblastic meningioma. The cerebral arterial occlusion secondary to the brain tumor should be caused by the compression of the vessels and the hemorrhage of the tumor. This case is rarely reported.

Adult↗