Biomedical subjects

R Seemann

Publications and source records attributed to R Seemann.

21 records · Page 2Linked to original sources

PubMed1991

Propagation and properties of Kaposi's sarcoma-derived cell lines obtained from patients with AIDS: similarity of cultured cells to smooth muscle cells.

Cells derived from Kaposi's sarcoma (KS) were propagated in vitro using conditions which resulted in elimination of contaminating fibroblasts and the emergence of homogeneous cell populations which morphologically resembled smooth muscle cells and had neoplastic characteristics. In long-term culture, they differentiated into large ribbon-like cells with longitudinal fibrillarity of their cytoplasm. These fibrils stained red by Masson trichrome staining, and were reactive with antibodies to desmin. Dense bodies typical of myoblasts were observed in some cells by electron microscopy. The cells did not form capillary structures like endothelial cells, they lacked Weible-Palade bodies, and did not express the blood-clotting Factor VIII-related antigen or receptors for the lectin Ulex europaeus agglutinin I. They did express four other antigens, however, in common with endothelial cells. The cells did not form tumors in athymic nude mice; however, they formed colonies in soft agar, manifested tumor-like growth on muscle organ cultures, and were invasive in an artificial basement membrane invasion assay. The results indicate that a component of KS is closely related to leiomyoblasts and and has neoplastic properties.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Differences in the salivary glycan pattern between children with high and low caries susceptibility.

Interactions between bacterial adhesins of lectin type and the oligosaccharide part of immobilised glycoconjugates on the tooth surface are involved in the specific colonisation of teeth. The specificity of the adhesion process is determined by the carbohydrate specificity of the bacterial lectins and the availability of the corresponding glycosylation pattern. On the other hand the same carbohydrate structures can specifically prevent the binding of bacteria by competitively blocking their adhesion, if sufficient amounts of this distinct carbohydrate structure are available in the secretion. Since carbohydrate binding receptors are also involved in the colonisation of tooth surfaces by cariogenic bacteria, it has been suggested that the architecture of the oligosaccharide portion of soluble glycoconjugates in saliva may play an important role as a constitutional host defence factor in the aetiology of dental caries. Characterising the availability of distinct carbohydrate patterns in saliva by using a pattern of well-described lectins in a competitive lectin inhibition assay we show that in children of a population-based sample a high caries susceptibility is associated with a reduced binding inhibition against the lectin peanut agglutinin (PNA). PNA is specific for the presence of terminal galactosyl residues and binds to the same O-glycan fractions as a surface lectin from Streptococcus mutans. The data suggest that a reduced availability of glycosylation patterns of galactosyl residues detected by the lectin PNA may act as an additional host-derived factor for an increased caries susceptibility.

Acetylgalactosamine↗

PubMedDate not supplied

A novel in vitro microbial-based model for studying caries formation--development and initial testing.

We report on the development and the initial testing of a new microbial-based caries model. Specimens were fixed on a rotating mount within a reaction chamber hermetically surrounded by a sterilised glove box. A cariogenic environment was obtained by inoculation with Streptococcus mutans (ATCC 25175) combined with a continuously repeating supply of sucrose solution, trypticase soy broth and artificial saliva applied by dripping. Twenty-five caries-free upper premolars were used. The mesial parts of the occlusal fissures had been sealed with a resin-based fissure sealant (test group 1). To produce marginal gaps, the distal parts had been moistened with saliva before resin application (test group 2). Five teeth served as control and were exposed to all fluids under sterile conditions before being removed from the system after 7 days. Test specimens were infected with S. mutans and were incubated for another 14 days. No unintentional contamination occurred during the 3-week period of operation. Demineralizations were evaluated by using confocal laser scanning microscopy. Only the test specimens showed clearly visible signs of biofilm formation and caries-like lesions. The mean primary lesion depth did not differ significantly between test groups. Wall lesion depths and surface areas of demineralizations underneath the fissure sealants were significantly higher in test group 2. Thus, our model allows the simultaneous production of primary and secondary caries-like enamel lesions in a considerable number of specimens and facilitates the possibility to manipulate and transfer them without necessarily terminating the experiment, opening new possibilities for in vitro caries research.

Bicuspid↗