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Biomedical subjects

M Richter

Publications and source records attributed to M Richter.

At least 415 records · Page 23Linked to original sources
PubMed1975

[Odontogenic keratocysts].

Keratocysts may develop from cellular multiplication, from recidivating growth of epithelial cells left after curettage, and they have an important potential growth, they can degenerate into malignancies. There are several etiological possibilities: tissues connected with crown formation, invagination of nucous epithelium, degeneration of follicular cysts producing keratin. The most important characteristic of these cysts is the frequent recidivation. Fron a clinical standpoint, they are classified as benign tumors. After enucleation, the walls of healthy tissue should be reduced, particularly in locations where the access of curettes is difficult. If necessary, apicetomy is performed in order to completely eliminate the cyst walls. Histological examination is mandatory. Finally, radiologic controls during at least six years should be made.

Adult↗
PubMed1975

Cells involved in the immune response. XXIX Establishment of optimal conditions for the primary and secondary immune responses by rabbit lymphoid cells in vitro.

Attempts were made to initiate the primary and secondary humoral immune responses to sheep red blood cells (SRBC) in vitro as determined by the hemolytic plaque-forming cell (PFC) response, with cell suspensions prepared from a variety of lymphoid organs of the rabbit- thymus, bone marrow, spleen, appendix, sacculus rotundus, Peyer's patches, popliteal lymph node and circulating leukocytes. A number of different media and gaseous phases were utilized in order to establish the optimal conditions for the immune response in vitro. The induction of a secondary PFC response was consistently obtained with 'memory' spleen cells obtained from rabbits 3-6 months following intravenous immunization with SRBC but not with cells of any of the other lymphoid organs, and this response probably represents the activity of memory cells which reside in the rabbit spleen. A primary response was observed only with 'normal' spleen cells, and the medium which faciliated the response was different from that which facilitated the induction of the secondary response in vitro. It was also observed, using a medium in which normal spleen cells were incapable of generating PFC', that mixed cultures of normal spleen and normal appendix or bone marrow cells could give a marked PFC reponse in vitro. Whether the PFC response to SRBCs obtained with the lymphoid cells of normal, unimmunized rabbits represent a true primary response, a secondary response, or a response of a different nature as a consequence of continuous subthreshold immunization of the rabbit with enteric microorganisms which cross-react with the antigen, remains to be determined. However, out initial successes with cultures consisting of cells of at least two distinct lymphoid organs in cases where the cells of any one of these organs could not respond, suggest that interaction of at least two functionally distinct cells is required and that the repsonse observed in vitro is probably a primary immune response.

Animals↗
PubMed1975

Cells involved in the immune response. XXVIII. the cellular composition of the lymphoid organs in the normal outbred rabbit.

Horse anti-rabbit spleen cell antiserum was obtained by the intravenous immunization of horses with rabbit spleen cells. The antisera obtained were analysed for their lymphocytotoxic activity with respect to the lymphoid cells of the different lymphoid organs prior to and following absorption with the different lymphoid cells. The results have been integrated with those obtained in previous investigations and an all-embracing concept of the interrelationship of the lymphoid cells in the different lymphoid organs in the rabbit has emerged. The distinction between the heretofore considered central lymphoid organs (bone marrow and thymus) and peripheral lymphoid organs (spleen, lymph node and appendix) has been blurred by the finding that, at least in the rabbit, appendix cells possess specific antigen markers and participate in cell-mediated immune reactions in vitro and the observation that the spleen also has a central lymphoid function in the generation of cells in vivo capable of carrying out a cell-mediated immune reaction in vitro. It is concluded that the distinction of central and peripheral lymphoid function may be an artificial one in that it may reflect a function of the particular organ in only one of the many different types of immune reactions and that it should not influence the investigator in the elucidation of the cellular mechanisms participating in the mediation of the different immune responses.

Absorption↗
PubMed1975

Naturally occurring immunosuppressive agents. I. The presence in normal pig liver of a factor possessing immunosuppressive properties with respect to pig lymphoid cells in vitro.

Saline cell-free extracts of normal pig liver, but not normal pig spleen, contain a noncytotoxic factor (or factors) capable of suppressing the blastogenic response of pig lymphocytes to stimulation with a number of plant mitogens: phytohemagglutinin, pokeweed, and concanavalin A. This reaction is generally considered to be a reflection of the capacity of the cell to participate in an immune reaction. Normal pig serum does not display inhibitory activity. The liver extract must be in contact with the lymphocytes for at least the final 48 hr of the 72-hr culture period in order to suppress the blastogenic response. Whether this active constituent in normal pig liver extract is an immunosuppressive agent in vivo remains to be determined.

Animals↗