scholarly journals Illustration of Pneumococcal Polysaccharide Capsule during Adherence and Invasion of Epithelial Cells

2005 ◽  
Vol 73 (8) ◽  
pp. 4653-4667 ◽  
Author(s):  
Sven Hammerschmidt ◽  
Sonja Wolff ◽  
Andreas Hocke ◽  
Simone Rosseau ◽  
Ellruth Müller ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Capsular Polysaccharide ◽  
A549 Cells ◽  
The State ◽  
Fixation Method ◽  
Fixation Procedure ◽  
Pneumococcal Infections ◽  
Electron Microscopic ◽  
Polysaccharide Capsule ◽  
Microscopic Studies

ABSTRACT The capsular polysaccharide of Streptococcus pneumoniae represents an important virulence factor and protects against phagocytosis. In this study the amount of capsular polysaccharide present on the bacterial surface during the infection process was illustrated by electron microscopic studies. After infection of A549 cells (type II pneumocytes) and HEp-2 epithelial cells a modified fixation method was used that allowed visualization of the state of capsule expression. This modified fixation procedure did not require the use of capsule-specific antibodies. Visualization of pneumococci in intimate contact and invading cells demonstrated that pneumococci were devoid of capsular polysaccharide. Pneumococci not in contact with the cells did not show alterations in capsular polysaccharide. After infection of the cells, invasive pneumococci of different strains and serotypes were recovered. Single colonies of these recovered pneumococci exhibited an up-to-105-fold-enhanced capacity to adhere and an up-to-104-fold-enhanced capacity to invade epithelial cells. Electron microscopic studies using a lysine-ruthenium red (LRR) fixation procedure or cryo-field emission scanning electron microscopy revealed a reduction in capsular material, as determined in detail for a serotype 3 pneumococcal strain. The amount of polysaccharide in the serotype 3 capsule was also determined after intranasal infection of mice. This study illustrates for the first time the phenotypic variation of the polysaccharide capsule in the initial phase of pneumococcal infections. The modified LRR fixation allowed monitoring of the state of capsule expression of pathogens during the infectious process.

Mise en évidence du rôle, dans la régénération des Amphibiens, d'une glycoprotéine sécrétée par la cape apicale: étude cytochimique et autoradiographique en microscopie électronique

Development ◽  
1974 ◽  
Vol 32 (1) ◽  
pp. 133-145
Author(s):  
Par Claude Chapron
Keyword(s):  
High Resolution ◽  
Epithelial Cells ◽  
Limb Regeneration ◽  
Target Cells ◽  
Silver Particles ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
High Resolution Autoradiography

Evidence for the role of an apical cap glycoprotein in amphibian regeneration: cytochemical and autoradiographic electron-microscopic studies Early during limb regeneration in the newt, an ectodermal apical cap covering a mesodermal blastema is formed. High-resolution autoradiography of these tissues has been carried out after incorporation of [3H]fucose, which is a precursor of glycoproteins. Autoradiography shows that silver particles are located at first on epithelial cells, then on mesenchymatous cells. This observation is consistent with a hypothesis in which the apical cap would elaborate a glycoprotein acting on the blastema. Substructural autoradiography and cytochemistry also show the importance of cellular surfaces for both cells producing glycoprotein and those which are target cells.

Electron Microscopic Studies of Fillers in Rubber. III. Effect of Milling on the Dispersion of Fillers

1956 ◽  
Vol 29 (3) ◽  
pp. 1003-1010 ◽  
Author(s):  
Eiji Suito ◽  
Masafumi Arakawa ◽  
Hiroshi Hasegawa ◽  
Yonemasa Furusawa
Keyword(s):  
Electron Microscope ◽  
Marked Effect ◽  
The State ◽  
Replica Method ◽  
Interesting Problem ◽  
Electron Microscopic ◽  
Vulcanized Rubber ◽  
Microscopic Studies ◽  
Filler Particles ◽  
The Relationship

Abstract In the study of types of fillers which have a marked effect on the properties of rubber, information as to how the filler particles are dispersed in rubber is a prerequisite. The authors have already reported on the state of dispersion of various fillers in vulcanized rubber, observed under an electron microscope by the replica method. How the dispersion of these fillers affects the properties of rubber is an interesting problem. Since, in the earlier work, filler particles were observed to orient themselves in certain directions, in this report the relationship between the state of dispersion observed under an electron microscope of filler particles in rubber milled in different ways and the resulting characteristics of the mixtures were examined.

scholarly journals Reduction in Capsular Content and Enhanced Bacterial Susceptibility to Serum Killing of Vibrio cholerae O139 Associated with the 2002 Cholera Epidemic in Bangladesh

2005 ◽  
Vol 73 (10) ◽  
pp. 6577-6583 ◽  
Author(s):  
Firdausi Qadri ◽  
Ann-Mari Svennerholm ◽  
Sohel Shamsuzzaman ◽  
Taufiqur Rahman Bhuiyan ◽  
Jason B. Harris ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Capsular Polysaccharide ◽  
Bactericidal Effect ◽  
Electron Microscopic ◽  
Recent Infection ◽  
Phenotypic Properties ◽  
Immunological Responses ◽  
Serum Killing ◽  
Vibrio Cholerae O139 ◽  
Microscopic Studies

ABSTRACT Vibrio cholerae O139 emerged in 1992 as a major cause of epidemic cholera. However, the incidence of disease due to this new serogroup subsequently decreased for almost a decade. In April 2002, there was a dramatic resurgence of V. cholerae O139 in Bangladesh. We compared the phenotypic properties of the bacterial isolates and the immunological responses in patients with disease due to V. cholerae O139 during the 2002 epidemic with those dating to the emergence of this disease in 1993 to 1995. Strains isolated from patients in the two time periods were compared with respect to capsular polysaccharide, their resistance to the bactericidal effect of serum, and their capacity to be used as target strains in complement-mediated vibriocidal assays. Phase-contrast microscopy showed that strains isolated in 2002 had less capsular material than those isolated from 1993 to 1995 (P = <0.001), a finding confirmed by electron microscopic studies. Strains isolated in 2002 were more susceptible to the bactericidal activity of serum compared to strains from 1993 to 1995 (P = 0.013). Compared to results using a standard O139 strain, a modified vibriocidal assay utilizing a 2002 strain, CIRS 134, as the target organism detected higher vibriocidal responses in both O139-infected cholera patients as well as O139 vaccine recipients. The vibriocidal assay utilizing the less encapsulated 2002 strain, CIRS 134, is a more sensitive indicator of adaptive immune responses to recent infection with V. cholerae O139. Consequently, this assay may be useful in studies of both O139-infected patients and recipients of O139 vaccines.

scholarly journals ELECTRON MICROSCOPY OF THE BURSA OF FABRICIUS OF THE EMBRYONIC CHICK WITH PARTICULAR REFERENCE TO THE LYMPHO-EPITHELIAL NODULES

1962 ◽  
Vol 13 (1) ◽  
pp. 127-146 ◽  
Author(s):  
G. Adolph Ackerman
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Embryonic Development ◽  
Golgi Complex ◽  
Bursa Of Fabricius ◽  
Cortical Region ◽  
Electron Microscopic ◽  
Submicroscopic Structure ◽  
Microscopic Studies ◽  
Pass Through

Electron microscopic studies of the bursa of Fabricius during the 15th and 16th day of embryonic development in the chick have shown the following findings in the submicroscopic structure of the cellular elements of the lympho-epithelial follicles. In the medulla, basal endodermal epithelial cells undergo mitosis and differentiation into lymphoblasts. During this transformation, there is a reduction in the amount of rough endoplasmic reticulum, an increase in the number or ribosomes, and frequently an enlargement of the Golgi complex. As lymphoblasts differentiate into medium lymphocytes there is a loss of endoplasmic reticulum, a reduction in the number of ribosomes and in the size of the Golgi complex, as well as a decrease in the number and size of mitochondria and in the size of the cell and nucleus. Cytoplasmic processes of reticular-epithelial cells extend between proliferating lymphocytic cells. Desmosomes connect stellate reticular-epithelial and basal epithelial cells but are not present in lymphocytic cells. Nuclear blebbing and vesiculation are frequently observed in the various cell forms of the developing lympho-epithelial nodules. Although lymphocytes and lymphocytopoietic activities in the cortex are sparse during this stage of embryonic development of the bursa, transitional forms between mesenchymal cells and lymphoblasts have been encountered. In addition, lymphoblasts and/or undifferentiated epithelial cells occasionally may pass through the basement membrane from the medulla into the cortical region of the developing nodule. That lymphocytes in the bursa of Fabricius originate from both endodermal and mesodermal derivatives during embryonic development appears to be consistent with both light and electron microscopic observations.

Elevated expression of hexokinase II protects human lung epithelial-like A549 cells against oxidative injury

2002 ◽  
Vol 283 (3) ◽  
pp. L573-L584 ◽  
Author(s):  
Aftab Ahmad ◽  
Shama Ahmad ◽  
B. Kelly Schneider ◽  
Corrie B. Allen ◽  
Ling-Yi Chang ◽  
...  
Keyword(s):  
Glucose Utilization ◽  
Human Lung ◽  
A549 Cells ◽  
Vector System ◽  
Hexokinase Ii ◽  
Electron Microscopic ◽  
Activity Measurements ◽  
Lung Epithelial ◽  
Elevated Expression ◽  
Microscopic Studies

Increased glucose utilization and hexokinase (HK)-II expression are adaptive features of lung cells exposed to hypoxia or hyperoxia. HK-II is the most regulated isoform of HK. Whether its overexpression could be protective against oxidative stress was explored in human lung epithelial-like (A549) cells. HK-II was overexpressed in A549 cells in a tetracycline-repressible retroviral vector system. Elevated expression of HK-II was confirmed by Western blot and activity measurements. Cell death caused by exposure to hyperoxia was decreased in HK-II-overexpressing cells. This effect was reversed when HK-II expression was suppressed with doxycycline. A similar protective effect was observed in HK-II-overexpressing cells after treatment with 1 mM hydrogen peroxide for 48 h. At baseline, fluorescence microscopy showed that overexpressed HK-II was localized to mitochondria. Electron microscopic studies showed that hyperoxia-exposed HK-II overexpressors had better-preserved and quantitatively smaller mitochondria than those in which the HK-II expression was suppressed or in the nontransduced A549 cells. Mitochondrial membrane potential was increased in HK-II-overexpressing cells exposed to hyperoxia compared with the nontransduced control cells under similar conditions. The present study demonstrates that HK-II protects human lung epithelial-like A549 cells against oxidative insults by protecting the mitochondria.

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