Search PubMed⌕ Search

Biomedical subjects

R C Oliver

Publications and source records attributed to R C Oliver.

At least 37 records · Page 2Linked to original sources
PubMed1983

The Minnesota dental practice analysis system.

The Minnesota Dental Practice Analysis System (DPAS) is a three-year project sponsored cooperatively by the University of Minnesota's School of Dentistry, Health Services Research Center, and the Minnesota Dental Association. The primary intent of the DPAS is to generate timely, reliable information on dental practice conditions for dental work force planning efforts. The system semiannually collects data from a representative sample of Minnesota dentists to monitor trends in such important areas as practice productivity, auxiliary utilization, types of procedures performed, payment mechanisms, and dental fees. Preliminary results of the project indicate that, in comparison with 1980 indicators, overall practice conditions among established Minnesota dentists have declined.

Adult↗
PubMed1982

Mechanism of Fc-mediated interaction of eosinophils with immobilized immune complexes: I. Effects of inhibitors and activators of eosinophil function.

A protein of apparent molecular weight 55000, designated protein 3, becomes newly detectable on the eosinophil surface as a specific consequence of interaction with antigen-antibody complexes immobilized in agar layers. The effect of various agents upon this interaction has been determined by monitoring the appearance of this protein by lactoperoxidase-catalysed iodination. Other parameters that have been measured include: the attachment of eosinophils to the agar layers and their subsequent degranulation, as measured by the release of granule peroxidase, and the degree of spreading of the eosinophils, as assessed by electron microscopy. Attachment of eosinophils to antibody-coated layers is inhibited by heat-aggregated immunoglobulin G (IgG), suggesting that this attachment is mediated via eosinophil Fc receptors. In addition, agents, such as the eosinophil chemotactic factor Ala-Gly-Ser-Glu, that enhance the expression of Fc receptors also enhance the appearance of protein 3, while agents, such as hydrocortisone, that inhibit the expression of Fc receptors reduce its appearance. It is concluded that the appearance of protein 3 parallels the expression of Fc receptors. Attempts to block the Fc region of the bound antibody with staphylococcal protein A were not successful. These experiments indicated that the Fc region of bound IgG has different binding sites for protein A and for the Fc receptor. The correlation between the appearance of protein 3 and subsequent degranulation of the eosinophils was confirmed by the use of agents, such as cytochalasin D and levamisole, that enhance both the appearance of protein 3 and degranulation. Conversely, hydrocortisone reduces the appearance of protein 3 and inhibits degranulation. Protein 3 does not appear when eosinophils adhere to agar layers coated with concanavalin A instead of antibody and the eosinophils do not degranulate. Addition of the calcium ionophore A23187, while causing the release of granule peroxidase, does not elicit the appearance of protein 3. These observations provided additional evidence that the appearance of protein 3 is a specific consequence of the interaction of eosinophils with antibody-coated surfaces. The fact that protein 3 appears at the eosinophil surface as a direct consequence of the interaction with antibody suggests that this protein is closely associated with the eosinophil Fc receptor. The enhancement of the appearance of protein 3 in the presence of cytochalasin D indicates that the movement and reorientation of both this protein and the Fc receptor are constrained by association with cytoplasmic microfilaments.

Antigen-Antibody Complex↗
PubMed1982

The mechanism of Fc-mediated interaction of eosinophils with immobilized immune complexes. II. Identification of two membrane proteins, modified by the interaction.

Human peripheral blood eosinophils attach to and flatten down onto antibody-coated surfaces and subsequently degranulate. An antibody-coated surface was prepared by treating a layer of agar, containing tetanus toxoid antigen and eosinophil chemotactic factor (ECF), with human anti-tetanus immunoglobin. Changes in eosinophil surface proteins during attachment to the antibody-coated agar layer were detected by lactoperoxidase catalysed iodination. Purified eosinophils were pre-treated with unlabelled iodide, lactoperoxidase and hydrogen peroxide to block pre-existing accessible tyrosine residues on the cell surface. They were then allowed to interact with the agar layer, and subsequently treated with lactoperoxidase and 125I-labelled iodide to label newly accessible surface proteins. Separation of the radioactive proteins by sodium dodecyl sulphate/polyacrylamide gel electrophoresis revealed that, while incubation of the cells in suspension restored the major proteins to the cell surface, interaction with the antibody-coated agar layer caused the appearance of additional proteins of apparent molecular weight 55K, 30K, 28K and 18K. The 55K, 28K and 18K proteins were greatly reduced when antibody was absent, but the 55K protein was distinguishable from immunoglobulin G (IgG) heavy chain, since it could be detected in low amounts even in the absence of antibody. It was found in purified plasma membranes and it could be separated from IgG heavy chain by iso-electric focusing. The possibility is discussed that this protein is either linked to the receptor for the Fc portion of IgG, or that it is itself the receptor. The 18K protein required both antibody and ECF for maximum expression, but was seen in limited amounts with ECF alone. Possibly it is concerned with an ECF-mediated recognition of IgG. Unlike the 55K protein, it binds concanavalin A. Plasma membranes were prepared from eosinophils by lysis in borate, followed by purification on a glass-bead column. Both the 55K and the 18K proteins were found to be major components of the eosinophil membrane.

Antigen-Antibody Complex↗
PubMed1980

The interaction of human eosinophils and neutrophils with non-phagocytosable surfaces: a model for studying cell-mediated immunity in schistosomiasis.

A model has been developed to simulate the surface of an antibody-coated schistosomulum. It consists of a layer of agar, containing antigen (tetanus toxoid) and a chemotactic factor (ECF). Some layers were coated with human anti-tetanus immunoglobulin. The mode of adherence of human eosinophils and neutrophils to these agar layers and the subsequent degranulation of the cells exactly paralleled the interaction of these cell types with antibody-coated schistosomula of Schistosoma mansoni. In particular, eosinophils made much more intimate contact than did neutrophils, and lysosomal enzymes were secreted extracellularly by direct fusion of granules with the plasma membrane of the cell. Biochemical evidence was also obtained for the secretion of enzymes during degranulation and the rate of enzyme release was found to be enhanced in the presence of specific antibody. This model, non-phagocytosable surface has the potential to provide basic information of the mode of action of effector cells in cell-mediated cytotoxic reactions against a wide range of parasites by incorporation of different factors into the agar layers.

Agar↗
PubMed1980

Eosinophil interaction with antibody-coated, non-phagocytosable surfaces: changes in cell surface proteins.

Plasma membrane changes during the interaction of human eosinophils with large, antibody-coated, non-phagocytosable surfaces have been investigated in a model system. Human peripheral blood eosinophils were incubated with layers of agar into which teranus toxoid (ECF), were incorporated. Changes in organization of the eosinophil plasma membrane proteins during interaction with the agar layer were detected by lactoperoxidase-catalysed iodination with [125]iodide. A protein of apparent mol. wt 55 000 became newly accessible on the eosinophil surface as a specific consequence of interaction with antigen-antibody complexes in the agar layer. This protein appeared in the early attachnent phase of the interaction which preceded extracellular degranulation. Cytochalasin D enhanced its appearance, while Mg2+-deficiency prevented it. A second newly accessible protein of apparent mol. wt 58 000 was blocked when ECF was present and may therefore be a receptor for ECF. Other proteins of apparent mol. wt 68 000 and 46 000 newly appeared at the surface of eosinophils even after incubation in suspension, apparently as a consequence of the rapid cycling of membrane components which occurs in eosinophils.

Agar↗
PubMed1977

Patient evaluation.

Failure to diagnose periodontal disease is a frequent and unnecessary error. A new periodontal screening examination has been proposed that will accurately detect periodontal disease in approximately five minutes and can be incorporated into a routine dental examination. Simplified treatment planning based on the findings of the periodontal screening examination has also been proposed. Its use could significantly improve the quality of periodontal care for most dental patients.

Adolescent↗
PubMed1977

Changes in the surface properties of rabbit polymorphonuclear leucocytes, induced by bacteria and bacterial endotoxin.

Rabbit peritoneal polymorphonuclear leucocytes were induced to aggregate by a variety of bacterial species. In the absence of serum, Gram-negative bacteria were more effective at inducing aggregation than Gram-positive. The most effective micro-organism tested, Acinetobacter sp. 199A, was readily phagocytosed and also induced extracellular secretion of the granule enzymes peroxidase and lysozyme. Isolated endotoxin from this bacterial species was highly effective in inducing aggregation and granule enzyme release. Endotoxin-induced aggregation was associated with a large increase in the amount of lactoperoxidase-catalysed iodination of surface protein. Only one iodinatable protein was detected, of molecular weight 150 000. It is postulated that phagocytosis of Gram-negative bacteria, followed by granule enzyme release, accelerates the rate of membrane recycling and that this brings new adhesive protein to the surface more rapidly.

Animals↗
PubMed1977

Endotoxin-induced platelet aggregation and secretion. II. Changes in plasma membrane proteins.

Responses of blood platelets to bacterial endotoxin lipopolysaccharide (LPS) have been correlated with changes in the molecular organization and composition of the platelet plasma membrane proteins. Binding of LPS, which occurred in the absence of Ca2+, was distinguished from platelet aggregation and degranulation, which required Ca2+ and plasma proteins. Changes in membrane organization were detected by double-labelling with [125I] and [131I] iodide, mediated by lactoperoxidase and hydrogen peroxide. Changes in total membrane composition were detected by gel electrophoresis of isolated membranes. Binding of LPS was associated with increased accessibility of a protein of mol. wt. 80000 to iodination. After aggregation and degranulation there was, in addition, increased accessibility of proteins of mol. wt. 68000 and 48000. Isolated membranes from LPS-stimulated platelets contained more of a protein of mol. wt. 200000 and less of a protein of mol. wt. 220000 than control membranes prepared from unstimulated platelets in the presence of cAMP and aminophylline. The relationship of the modified plasma membrane proteins to the contractile proteins of the platelet and their possible redistribution in the cell during aggregation and secretion is discussed.

Acinetobacter↗
PubMed1976

Lysis and killing of bacteria by lysosomal proteinases.

The bacteriolytic and bactericidal effects of the human proteinases cathepsin B, cathepsin D, cathepsin G, and elastase were investigated. Cathepsin G and elastase were 5 to 10% as active as egg white lysozyme in the lysis of Micrococcus lysodeikticus. All four enzymes slowly lysed the lysozyme-resistant Staphylococcus aureus. The gram-negative Acinetobacter 199A was rendered sensitive to lysozyme by all of the proteinases. Only elastase caused marked proteolysis of the outer membrane, which would permit access by lysozyme to the underlying peptidoglycan. When the surface layer of regularly arranged a protein was removed, however, the outer membrane proteins became susceptible to the other proteinases. Cathepsin G, elastase, and cathepsin D were bactericidal to Acinetobacter 199A. The bactericidal activity of cathepsin D was shown to be dependent on enzymatic activity, unlike that of cathepsin G, which was related to its cationic nature.

Acinetobacter↗
PubMed1976

Synthesis and turnover of the regularly arranged surface protein of Acinetobacter sp. relative to the other components of the cell envelope.

The formation of the components of the cell envelope of Acinetobacter sp. 199A was investigated by measuring the incorporation of [3H]leucine into protein, [14C]galactose into lipopolysaccharide, 32P into phospholipid, and [3H]diaminopimelic acid into peptidoglycan. Whereas the lipopolysaccharide and intrinsic protein of the outer membrane were stable, some of the regularly arranged surface protein, the alpha-protein, was lost into the growth medium. Only newly synthesized alpha-protein was lost. The peptidoglycan of the murein layer was also labile. Selective inhibition of the formation of individual components of the cell envelope with penicillin, chloramphenicol, and bacitracin showed that incorporation of protein into the outer membrane required the simultaneous formation of complete lipopolysaccharide. The converse was not true: protein synthesis was not required for lipopolysaccharide incorporation. Formation of the outer membrane and the murein layer proceeded independently.

Acinetobacter↗
PubMed1976

A periodontist's view on the assessment of periodontal disease in the community.

Periodontal treatment differs from other forms of dental treatment in that it demands long term cooperation from the patient without which the dentists' efforts are largely without value. The earliest stage of periodontal disease is gingivitis which is characterized by bleeding on gentle probing. It is a reversible condition which, depending on many poorly understood factors, may or may not progress to periodontal disease. This stage is characterized by the apical migration of junctional epithelium, pocket formation and loss of alveolar bone. Pocket depth, though not indicating the presence of active disease, is the best available measure of periodontal disease. In school children the majority of disease is gingivitis which can be largely eliminated by plaque control which they should be taught to practise from themselves. In adults a screening procedure has been developed which will rapidly identify those in need of treatment. Patients with gingivitis can be referred to hygienists. Those with moderately advanced disease are scheduled for non-surgical periodontal therapy which should be followed by re-evaluation and redefinition of the treatment plan. Those with advanced periodontal disease are usually referred for specialist treatment. It has been shown that pockets of up to 5 mm in depth can be maintained without further destruction by plaque control combined with scaling and root planing. The most important aspect of periodontal health remains the quality of long term maintenance care and the motivation of the patient to accept responsibility for it.

Adolescent↗