Biomedical subjects
Publications and source records attributed to Z Metzger.
A procedure is described for the construction of composite resin veneers for large amalgam restorations. The resulting restoration combines the physical qualities of amalgam with the esthetic benefits of composite resins. Among the 14 restorations that have been studied for 2 years, none failed mechanically and minor surface discolorations have been satisfactorily corrected by polishing.
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Explore the source record for details and available documents.
The regulation by prostaglandin E2 (PGE2) of production of oxygen radicals by bacterial lipopolysaccharide-(LPS) activated macrophages was studied in vitro. A 48-hr incubation of murine thioglycollate-elicited macrophages with LPS (0.1 micrograms/ml) resulted in an enhanced ability of these cells to produce oxygen radicals when challenged with phorbol myristate acetate (PMA). Macrophages incubated for 48 hr without LPS did not produce measurable amounts of oxygen radicals when exposed to this triggering stimulus. Thus, PMA-triggered production of oxygen radicals was the result of macrophage activation by LPS. The PMA-triggered production of oxygen radicals by the LPS-activated macrophages was inhibited when PGE2 (10(-5) to 10(-9) M) was present during the incubation with LPS. Inhibition by PGE2 occurred during the early stages of macrophage activation, since the addition of PGE2 24 hr after LPS no longer inhibited the production of oxygen radicals by the macrophages. This inhibitory effect of PGE2 on the LPS-induced activation of macrophages could be reproduced by cyclic-adenosine-monophosphate (cAMP) agonists, such as isoproterenol and cholera toxin as well as by the cAMP analog dibutyryl-cAMP, suggesting a cAMP-mediated mechanism for the inhibitory effect of PGE2 on macrophage activation by LPS. Previous reports have implicated prostaglandins as mediators of destructive processes associated with chronic inflammation. Our findings suggest that PGE2 may, on the other hand, reduce tissue damage in a chronic inflammatory site by inhibiting the production of oxygen radicals by macrophages activated in the sera.
This study was performed to see if adherent cell-derived toxic oxygen metabolites contribute to the suppression of mononuclear cell blastogenic responses in Hodgkin's disease. Peripheral blood mononuclear cells from 10 patients with Hodgkin's disease were stimulated in culture with the mitogen PHA in the presence of the prostaglandin inhibitor indomethacin and the antioxidants catalase or vitamin E. Patient lymphocytes showed significant increases in PHA-induced proliferation at all PHA doses when cultured with indomethacin. Further augmentation of lymphocyte proliferation was achieved with the addition of catalase or vitamin E to indomethacin in the culture system. The increases in proliferation seen on culture with these agents were greatest in patients with more depressed initial PHA responses. When adherent cells were removed before culture, the agents no longer facilitated increases in proliferation. These data suggest that abnormal lymphocyte proliferative responses seen in Hodgkin's disease may result in part from the excessive production of toxic oxygen metabolites as well as prostaglandins by adherent cell populations.
Therapeutic administration of tetracyclines, widely used antibiotic drugs, permanently labels layers of dentin that are calcifying at the same time. A method is described for detecting and photographing these stained layers of dentin. The presence of tetracycline-labeled dentin layers in the teeth of subjects of a forensic science investigation can be used for the individualization of specimens as well as to provide information about the age of the individual. When compared to medical records, the tetracycline-labeled dentin layers can also assist in establishing the identity of the subject. The interpretation of tetracycline-labeled dentin layers and its pitfalls are discussed.
Macrophage-mediated suppression of Con A induced proliferation of murine splenic lymphocytes was studied in vitro. Either Corynebacterium parvrum-induced peritoneal exudate cells (PEC) or thioglycollate-induced PEC could totally suppress lymphocyte proliferation at a PEC:lymphocyte ratio of 2:10, whereas a ratio of 1 to 1.5: 10 caused a partial (60 to 68%) suppression. Exogenous PGE1 and PGE2 at concentrations of 10(-8) to 10(-6) M could not totally suppress lymphocyte proliferation. Conversely, indomethacin reversed the partial suppression by macrophages but only partially protected the totally suppressed lymphocyte cultures. Macrophage-mediated cytotoxicity and cytostasis have been proposed to be mediated by hydrogen peroxide. Therefore, hydrogen peroxide was investigated as a possible additional cause for macrophage-mediated suppression, by testing the anti-inhibitory effects of catalase. Partially suppressed cultures were effectively protected from suppression by catalase. In totally suppressed cultures, catalase alone was only minimally effective, but a synergistic effect of catalase and indomethacin was obtained, which provided complete protection from maximal macrophage-mediated suppression. Catalase presumably contributes to the reversal of macrophage suppressive effects both by reducing the direct toxic effect of H2O2 and by preventing the H2O2 from generating additional prostaglandins.
Gustafson's method for age determination from teeth is based on the evaluation of ground sections of teeth. Six age-associated parameters are evaluated in the ground section and are compared to a regression curve of age versus the age-associated changes. Two of these changes, transparency of radicular dentin and secondary dentin, have the highest correlation with age. The evaluation of these parameters only from thin (0.25-mm) ground sections may lead to an artificially high "secondary dentin value." These artifacts may be caused by the attempt to include the whole pulp chamber and root canal in a 0.25-mm-thick ground section and by an accidental overgrinding of the apical area of the root, respectively. These artifacts were encountered occasionally even in ground sections prepared by highly trained personnel and became more frequent in ground sections prepared by a person who, though trained, did not use this technique daily. A modification of the data-collecting method is suggested to make possible the use of thick (1.0-mm) ground sections for the evaluation of most of the aging criteria, thereby eliminating the possible inaccuracies in the preparation and evaluation of the thin (0.25-mm) ground sections.
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