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Biomedical subjects

E Michels

Publications and source records attributed to E Michels.

At least 19 recordsLinked to original sources

Outcomes research.

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Health Services Research

Human resources.

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Humans

Levels of reduction.

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Central Nervous System

Use of the t test.

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Analysis of Variance

Electroelution of antigens immobilized on antibody-linked affinity matrices.

An electrophoretic elution procedure for desorption of antigens from antibody-linked gel matrices is described which is performed in a commercially available elution device. The technique presented does not involve denaturing conditions such as chaotropic reagents or low and high pH elution buffers. Comparison of electroelution and conventional elution with acidic buffer reveals that the techniques is especially suitable for monoclonal antibodies with high affinity for their ligands. Recovery of antigens after electroelution is significantly higher than by desorption with glycine-HCl, pH 2.5. There is no loss of antigens during post-elution procedures. Proteins are obtained in small elution volumes and can be desalted without sample transfer.

Angiogenesis Inducing Agents

[Sudden deafness and its therapy. Clinical study of 548 cases].

Analysis of 548 cases of sudden deafness shows impressively the importance of an infusion therapy with drugs improving the circulation which should be started as soon as possible. The greatest success could be made in the deep frequencies, whereas in the high frequencies the results were lower by nearly 8 decibels. Patients with sudden deafness on both sides or recurrent sudden deafness showed significantly less improvement of hearing than patients with first-time sudden deafness on one side. Remarkable is the continuous growth of sudden deafness in the low frequencies only, a phenomenon which was rarely seen one generation ago. Can this be interpreted as a change in the pattern of sudden deafness?

Adolescent

Murine alpha-2-macroglobulin: localization on a subpopulation of macrophages.

We have previously shown that mouse peritoneal macrophages synthesize and secrete alpha-2-macroglobulin (alpha 2M) in culture. We have now examined whether alpha 2M delineates a subpopulation of murine macrophages. Mouse alpha 2M was purified from plasma by gel filtration and immunoabsorption to remove IgM. Purified alpha 2M was an active proteinase inhibitor, had a pI of 4.8, and a relative molecular mass (Mr) of 765 kD which dropped to 194 kD on reduction. Antisera raised against mouse alpha 2M were not cross-reactive with guinea pig or human alpha 2M, or with antigens in guinea pig, human, bovine or equine serum. One to 18 per cent of freshly isolated bone marrow, resident peritoneal or induced peritoneal macrophages displayed immunoreactive cytoplasmic and surface alpha 2M as detected by single cell immunoperoxidase assay or flow cytometry. alpha 2M was not detected in or on thymocytes or bone marrow lymphocytes. In culture, bone marrow-derived macrophages displayed peak levels of cytoplasmic alpha 2M on day 7 and two peaks of surface alpha 2M on days 2-3 and 5-7. The fact that alpha 2M can function as an anti-proteinase, can modulate lymphokine production and is present on inflammatory macrophages suggests a regulatory role for macrophages bearing and secreting this molecule at tissue sites of inflammation.

Animals

A monoclonal antibody against an antigen present on mouse macrophages and absent from monocytes.

A monoclonal antibody (BM8) raised in the rat against cultured mouse bone marrow-derived macrophages reacted only with macrophages and not with granulocytes, mast cells, platelets, lymphocytes, fibroblasts, and endothelial cells. BM8 did not detect blood monocytes. In cultured bone-marrow cells, expression of BM8-antigen was found on a few macrophages after one day of culture and reached its maximum level with 80% positive macrophages after 7-10 days of culture. The antibody BM8 belonged to the IgG2a subclass, was non-cytotoxic and directed against a 125 kD membrane antigen. In cryostat sections of normal mouse tissues (spleen, lymph node, thymus, liver, skin) BM8 detected tissue-fixed macrophages and Langerhans cells in the skin. In spleen and lymph node, BM8 reacted with macrophages in the red pulp and in the medullary cords, respectively, but not with heavily phagocytosing marginal-zone macrophages, as revealed by in-vivo phagocytosis of colloidal carbon. In granulomata induced by complete Freund's adjuvant, BM8 detected inflammatory macrophages but not epithelioid cells. Thus, antibody BM8 detected a differentiation antigen expressed only on mature, tissue-fixed macrophages.

Animals

Functional characteristics of murine macrophages responding to migration inhibitory factors.

Mouse bone marrow cells differentiate in culture in the presence of L cell-conditioned medium to macrophages (M phi). Proliferation, release of plasminogen activator, expression of transglutaminase, random motility and response to a standard preparation of purified M phi migration inhibitory factor (MIF) was recorded daily up to 14 days. After an initial phase of proliferation, precursor cells differentiated into M phi. In the course of maturation, plasminogen activator production was transiently expressed between day 4 and 12; beginning on day 5 the cells expressed intracellular transglutaminase. Random motility of cells was high at the beginning of culture but steadily declined thereafter. The response to MIF was only expressed between day 5 and 8. However, it was possible to induce MIF responsiveness in mature, unresponsive M phi by the addition of L cell-conditioned medium. To characterize the MIF-responsive M phi type further, bone marrow-derived M phi at day 6 of culture were separated on a hypotonic Percoll gradient into three distinct cell bands. While all densities of M phi displayed random migration, only cells with a density between 1.060 and 1.065 were responsive to MIF. We conclude that the response of M phi to MIF is a phenotypic trait transiently expressed in the course of maturation.

Acyltransferases

Migration inhibitory factors and macrophage differentiation.

It has been described before that only certain types of macrophages are capable to respond to lymphokines and that only certain macrophage phenotypes were able to migrate and to respond to migration inhibitory factors (MIF). With respect to the dissociation of MIF activities from a series of other biological activities, and with regard to the phenotype-associated response of macrophages to MIF it was asked: What are the characteristics of the MIF-responsive macrophage phenotype and what are the functional changes induced by MIF on macrophages in addition to inhibition of random migration? Bone marrow-derived macrophages on day 6 of culture were separated by hypotonic Percoll density gradient centrifugation into three distinct bands and analyzed for a variety of functions. It was found that migrating and MIF-responsive macrophages accumulate at a certain density. These macrophages were further characterized by monoclonal antibodies generated against murine macrophage phenotypes. One marker was found to be preferentially expressed by MIF-responsive macrophages. In order to study the inducibility of MIF responsiveness, bone marrow-derived macrophages on day 16 of culture which were poorly migrating and did not respond to MIF were induced to proliferate by the addition of L cell-conditioned medium. After proliferation had subsided, MIF sensitivity was restored. The effects of MIFs other than migration inhibition, on a number of functions which had been mapped within the cell cycle, were investigated. It was found that MIF acts anti-proliferative on "young", cycling macrophages. Non-cycling, mature macrophages were shifted to a state characterized by a decreased expression of transglutaminase and plasminogen activator and an increase of certain phenotypic surface markers. It is concluded that MIFs are differentiation-inducing signals, acting on the generation of macrophages from precursors but also in the recruitment of terminally differentiated macrophages to "inflammatory" type of macrophages which are functional in the induction of immune responses.

Animals

Selection of the delayed hypersensitivity T effector and T suppressor cell response by antigen-presenting macrophages.

The T effector lymphocytes of delayed type hypersensitivity reactions (TDH) are regulated by a complex T suppressor (Ts) cell circuit. Induction of TDH cells requires Ia+ adherent cells as antigen-presenting cells. Little is known about the antigen presentation of the induction of Ts cells. We describe an experimental model in which TDH and Ts cells are induced separately by different antigen-presenting macrophages grown from bone marrow stem cells. Bone marrow derived macrophages grown in L cell-conditioned medium for various periods and labeled with 2,4-dinitrobenzene sulfonic acid differ in their ability to induce TDH and Ts cells in vitro. The functional activity of the two T subpopulations was assessed in vivo by epicutaneous challenge or sensitization with 2,4-dinitrofluorobenzene of mice receiving the in vitro educated cells. Ear swelling or suppression of swelling was recorded. It could be shown that 5-7 day bone marrow-derived DNP-labeled macrophages preferentially induced Thy 1+ Lyt 1+ antigen-specific TDH cells; 7-10 day old antigen-presenting bone marrow-derived macrophages induced preferentially Thy 1+ Lyt 2+ antigen specific Ts cells. Characterization of various phenotypic markers revealed different surface antigen expression and functional differences such as MIF responsiveness or transglutaminase activity on the two macrophage populations. These data support the concept that activation of the Ts regulatory circuit may require antigen presentation by specialized antigen presenting cells, characterized by certain surface and functional markers and different from those inducing preferentially TDH cells.

Animals