An animal model was presented to study periodontal disease in Osborne-Mendel rats with depressed indigenous oral flora. In connection with the inoculation of an erythromycin-resistant strain A. viscosus Ny 1 E after 40 experimental days only the animals showed plaque formation, bleeding from the gingival sulcus upon gentle probing and severe alveolar bone loss. 56% sucrose in the diet counteracted the establishment of A. viscosus Ny 1 E in dental plaques. As a consequence plaque formation, gingival bleeding and bone loss diminished. Plaque formation, gingival bleeding and bone loss were correlated.

Actinomyces↗

PubMed1978

The effect of cyclosporin A on dental caries in rats monoassociated with Actinomyces viscosus NY 1.

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Actinomyces↗

PubMed1977

Are Actinomyces viscosus antigens B cell mitogens?

An extracellular heteroglycan (ECHG) and a sonicated cell supernatant (SCS) of Actinomyces viscosus Ny 1 induced strong lymphocyte proliferation. This was shown with spleen and thoracic duct cells form germfree rats and confirmed with cells from conventional "nude" mouse spleens. Spleen cells developed direct plaque-forming cells against densely coupled TNP-SRBC. The mitogenic property of ECHG was diminished considerably after mild alkaline hydrolysis for lymphocytes form rat spleens and was totally abolished for cells from "nude" mouse spleens. These results suggest that ECHG and SCS have B cell mitogenicity.

Actinomyces↗

PubMedDate not supplied

Scanning tunneling and transmission electron microscopy on identical areas of biological specimens.

A methodology for tip and specimen-support manufacturing is described which allows for scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) on identical areas of biological specimens, at comparable resolution. Topographs and dI/ds-maps were used to investigate tip-specimen interaction on native air-dried phage T4 polyheads where individual capsomeres and structural alterations upon repetitive scans have been observed at a tunnel current of 0.5 pA.

Microscopy, Electron, Scanning↗

PubMedDate not supplied

Assembly of 2-D membrane protein crystals: dynamics, crystal order, and fidelity of structure analysis by electron microscopy.

Membrane protein reconstitution into two-dimensional (2-D) ordered arrays is described. The assembly of 2-D crystals may be modeled as a two-step process: the membrane protein is first integrated in the lipid bilayer and then crystallized by removal of excess detergent or lipid and/or by precipitating agents. Lipid-detergent, protein-detergent, and lipid-protein interactions are critical during the first step, while lipid-protein and protein-protein interactions dominate events in the second step. The evidence supporting this model results from quasielastic light scattering analyses and electron microscopy of different lipid-detergent systems and reconstitution experiments with Escherichia coli porin OmpF, Phormidium laminosum photosystem I reaction centers, and integral membrane proteins of mammalian lens fiber cells.

Animals↗