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Biomedical subjects

B Wagner

Publications and source records attributed to B Wagner.

At least 235 records · Page 13Linked to original sources
PubMed1984

Experimental infection with group B streptococci in tissue cages implanted in rabbits.

Using tissue cages subcutaneously implanted in rabbits an experimental group B streptococcal (GBS) infection was induced. The type Ia strain differed from the type III strain in producing a septicemic infection leading to the death of the animals on day 4 of infection. Active immunization with whole cells of the homologous strain resulted in phagocytosis and killing of the bacteria, whereas passive immunization only resulted in inhibition of the spread of the type Ia infection from the cages. Electron microscopy showed that in unprotected animals infection with either strains was followed by a lysis of erythrocytes and polymorphonuclear cells in the cage fluid. Opsonization by type-specific antibodies already present in the cage fluid preceded the phagocytosis of streptococci in the immunized animals. The tissue cage model offers a suitable way for studies of the pathogenesis of GBS infection. The different factors influencing the process of infection can also be easily monitored.

Animals↗
PubMed1984

The mouse ear inflammatory response to topical arachidonic acid.

Application of arachidonic acid (AA) (0.1-4 mg) to the ears of mice produces immediate vasodilatation and erythema (5 min) followed by the abrupt development of edema which is maximal at 40-60 min. The onset of edema coincides with extravasation of protein and leukocytes. After 1 h, the edema begins to wane rapidly and the inflammatory cells leave the tissue so that by 6 h the ears have returned to near normal except for residual erythema. During the period 6-48 h, AA-treated ears show a greatly diminished response with respect to edema and cell infiltrate when AA is applied a second time. Inhibitor studies show that the inflammatory response is due to formation of AA metabolites via both the cyclooxygenase and lipoxygenase pathways. Under appropriate conditions, AA-induced ear edema can be used as a model to screen for compounds showing in vivo lipoxygenase inhibitory activity. Although relatively large doses of AA were applied topically, there was only a modest stimulation of epidermal DNA synthesis and mitotic index with no consequent hyperplasia. Although arachidonic acid is capable of eliciting most aspects of an inflammatory response, the reaction is abrupt in onset and of short duration. Additional factors appear to be required to produce a prolonged inflammatory response with associated tissue destruction, or inflammatory cell activation and immobilization in situ.

Administration, Topical↗
PubMed1983

Electron microscopic localization of receptors for aggregated beta 2-microglobulin on the surface of beta-hemolytic streptococci.

The presence and location of receptors for aggregated human beta 2-microglobulin (beta 2m) on the surface of group A, C, and G streptococci were studied by electron microscopic techniques. Ferritin-conjugated aggregates of human beta 2m were used in direct binding experiments. Ferritin-conjugated antibodies against beta 2m were employed in a two-step indirect binding assay where the streptococci were incubated with unlabeled beta 2m aggregates before the addition of antibodies. Similar results were obtained with these two methods. Among tested group C and G strains, some showed binding of beta 2m, whereas others were negative. In group A streptococci, beta 2m binding was localized to filamentous structures typical of M protein. In two M protein-negative group A strains, the reactivity was heterogeneous, revealing a majority of unlabeled, but also some heavily labeled streptococci. Morphologically, these beta 2m-binding bacteria exhibited M protein-like projections in contrast to the smooth surfaces of unlabeled cells.

Cell Membrane↗
PubMed1983

Morphological evidence for different types of IgG-Fc receptors in group A streptococci.

The binding of immunoglobulin G (IgG) from man and 14 animal species to Group A streptococcal cells was studied by electron microscopy. Only the IgGs of rhesus monkey and guinea pig did not bind to any of the streptococcal strains tested. Fc receptors were seen located on filamentous protrusions of the streptococcal cell wall either regularly or in focal distribution. On the inner surface of isolated cell walls no Fc receptors were detected. Both the different labelling patterns for different IgG and the results of inhibition studies with homologous and heterologous IgGs suggested the existence of different types of Fc receptors in the same strain. Further characterization of the receptors, including their location, was performed by studying their susceptibility to several proteolytic enzymes.

Animals↗
PubMed1982

Growth of the mandible during pubescence.

Annual cephalometric radiographs of 67 children were used to analyze mandibular growth during pubescence. Annual increments were calculated for articulare-gonion (Ar-Go), articulare-gnathion (Ar-Gn) and gonion-gnathion (Go-Gn). Pubertal spurts were recorded for annual increments within two years of peak height velocity (PHV) that exceeded the immediately preceding increment by at least 1 mm (corrected for enlargement). Such spurts in mandibular dimensions are common but not universal. They were more common in the boys, but occurred about 1.5 years earlier in the girls. They tended to be larger in boys, although the mean increments in the two sexes were similar before and after the spurts. First pubertal spurts usually occur before PHV, but there was considerable variation in this relationship. Almost all first pubertal spurts occur after ulnar sesamoid ossification and before menarche. The variability of their timing was less in relation to PHV than in relation to skeletal age, menarche or ulnar sesamoid ossification. It can be desirable to determine whether a spurt has occurred in an individual patient. For this purpose, Greulich-Pyle skeletal age may be only slightly more meaningful than chronological age, and neither is sufficiently precise for many clinical applications.

Adolescent↗
PubMed1982

[Colony morphology of Clostridium perfringens type A (author's transl)].

At least 4 different colony form of Clostridium perfringens on the surface of yeast extract blood agar after overnight incubation were demonstrated. A: glossy colonies with entire margins, mostly surrounded by narrow zones of complete hemolysis and a much wider zone of incomplete hemolysis (colonies typical for C. perfringens (Fig. 1), B: dwarf colonies, similar to A, but very small (Fig. 2), C:rough colonies slightly raised with lobate margins (Fig. 3-4), D: flat colonies with irregular surface and filamentous margins (Fig. 5). Three strains out of 126 gave rise to glossy and rough colony forms (Fig. 6).

Agar↗
PubMed1982

Growth of group B streptococci and development of surface antigens in tissue cages implanted in rabbits.

Using tissue cages implanted in rabbits the growth of some strains of group B streptococci and the development of cell surface antigens were analyzed and compared to those under in vitro conditions. Two encapsulated strains grew well in the tissue cage fluid. Their capsules could be heavily labelled by ferritin-conjugated antibody against the type-specific polysaccharide. However, the thickness of the capsule was different to that following cultivation in vitro. In both strains the labelling of the group polysaccharide in the cell wall was sterically hindered by the large capsule. Two strains lacking a capsule did not grow in the tissue cage fluid but were mostly phagocytized. This again demonstrates the importance of the type-specific polysaccharides as significant virulence factors of group B streptococci.

Animals↗
PubMed1982

Electron microscopic study of the location of the Fc-reacting factor on group A streptococci.

The presence of the Fc-reacting factor was demonstrated on four out of five different group A Streptococcus strains using ferritin-labelled immunoglobulin G. A comparison of the results obtained by this electron microscopic technique with Fc-reacting factor detection results obtained with hydrochloric acid extracts of cells in passive haemagglutination on sensitized red cells, showed that not only hydrochloric acid extractable but also non-extractable Fc-reacting factor can be present on the group A Streptococcus cell. Out of several IgGs tested, only rabbit and swine IgGs bound to Fc receptors of group A Streptococcus walls. The Fc-reacting factor is ultrastructurally localized on the tips of the filamentous protrusions forming the outermost layer of the Streptococcus wall. The involvement of the Fc portion of IgG in the reaction was demonstrated by a positively reacting sandwich arrangement in which Streptococcus cells were incubated with rabbit antiferritin before being treated with ferritin.

Cell Wall↗
PubMed1982

Immunoelectron microscopic analysis of polysaccharide and protein surface antigens in wild strains of group B streptococci.

The ultrastructural location of the group polysaccharide, the type-specific polysaccharides and the protein antigens Ibc, R and X of freshly isolated strains of group B streptococci was studied by the direct immunoferritin technique. The results were compared with the findings in prototype strains representing the serological types of Streptococcus agalactiae. In some strains the group antigen was demonstrated over the entire cell surface, but in strains with a large type polysaccharide capsule labelling was confined to the equatorial zone of the cells. If the type polysaccharide was released by extraction, however, the group antigen of these strains was uncovered over the whole surface of the cell. The type polysaccharide capsule was not demonstrated by the conventional electron microscopic technique, but it was visualized after reacting with the homologous type-specific antibody. The extent and density of the polysaccharide capsule were found to differ in strains with the same type antigen. The type polysaccharide did not block demonstration of the simultaneous presence of protein antigens, implying that the two are arranged mosaic-wise inside the capsule.

Antigens, Bacterial↗