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Biomedical subjects

M Richter

Publications and source records attributed to M Richter.

At least 487 records · Page 27Linked to original sources
PubMed1969

Cells involved in the immune response. VI. The immune response to red blood cells in irradiated rabbits after administration of normal, primed, or immune allogeneic rabbit bone marrow cells.

Irradiated rabbits given allogeneic bone marrow cells from normal adult donors responded to an injection of sheep red blood cells by forming circulating antibodies. Their spleen cells were also capable of forming many plaques using the hemolysis in gel technique, and were also capable of undergoing blastogenesis and mitosis and of incorporating tritiated thymidine upon exposure to the specific antigen in vitro. However, irradiated rabbits injected with allogeneic bone marrow obtained from rabbits injected with sheep red blood cells 24 hr prior to sacrifice (primed donors) were incapable of mounting an immune response after stimulation with sheep red cells. This loss of reactivity by the bone marrow from primed donors is specific for the antigen injected, since the immune response of the irradiated recipients to a non-cross-reacting antigen, the horse red blood cell, is unimpaired. Treatment of the bone marrow donors with high-titered specific antiserum to sheep red cells for 24 hr prior to sacrifice did not result in any diminished ability of their bone marrow cells to transfer antibody-forming capacity to sheep red blood cells. The significance of these results, with respect to the origin of the antigen-reactive and antibody-forming cells in the rabbit, is discussed.

Animals↗
PubMed1969

Cells involved in the immune response, IX. Depletion from the normal rabbit bone marrow of antigen-reactive cells directed toward human peripheral leukocytes.

Normal adult rabbits were injected intravenously with peripheral leukocytes obtained from a normal human volunteer (donor A). The animals were sacrificed 24 hours later, and their bone marrow cells (primed bone marrow) or bone marrow cells obtained from a normal, unimmunized rabbit (normal bone marrow) were injected intravenously into irradiated (800 r) rabbits. The latter were immunized with peripheral leukocytes of donor A. The antisera obtained from the irradiated rabbits given primed bone marrow cells displayed minimal or no cytotoxic activity toward white cells of either donor A or an unrelated donor B. On the other hand, antisera obtained from irradiated rabbits given normal bone marrow cells displayed high titers of cytotoxic activity with respect to donor A cells only. It is concluded that rabbit bone marrow can be depleted of antigen-reactive cells directed toward white cell antigens following injection of the white cells intravenously and that these bone marrow cells are incapable of conferring antibody-forming capacity, in irradiated recipients, directed to this particular species of white cells. The relevance of these findings to the field of transplantation in general is discussed.

Animals↗
PubMed1969

Cells involved in the immune response. 13. The nature of the cellular interactions relating antibody formation and immunologic tolerance: a unified hypothesis.

The various cells and cell pathways involved in the induction of the primary humoral immune response have been discussed from the point of view of the unitary, as opposed to the multiple, pathway concept. The immunocompetent cells made unresponsive in the immunologically tolerant animal and the cells capable of responding with antibody formation were considered. It is concluded that there exist multiple cellular pathways through which the humoral immune response may be expressed.

Animals↗
PubMed1968

Cells involved in the immune response. IV. The response of normal and immune rabbit bone marrow and lymphoid tissue lymphocytes to antigens in vitro.

Cell suspensions of immune rabbit lymph nodes and spleen were capable of undergoing blastogenesis and mitosis and of incorporating tritiated thymidine when maintained in culture with the specific antigen in vitro. They did not respond to other, non-cross-reacting antigens. The blastogenic response obtained with immune lymph node cells could be correlated with the antibody synthesizing capacity of fragment cultures prepared from the same lymph nodes. Cell suspensions of immune bone marrow responded to non-cross-reacting antigens only whereas cell suspensions of immune thymus, sacculus rotundus, and appendix did not respond when exposed to any of the antigens tested. On the other hand, neither fragments nor cell suspensions prepared from lymph nodes, spleen, and thymus of normal, unimmunized rabbits responded with antibody formation and blastogenesis when exposed to any of the antigens. However, normal bone marrow cells responded with marked blastogenesis and tritiated thymidine uptake. The specificity of this in vitro bone marrow response was demonstrated by the fact that the injection of a protein antigen in vivo resulted in the loss of reactivity by the marrow cell to that particular antigen but not to the other, non-cross-reacting antigens. Furthermore, bone marrow cells of tolerant rabbits failed to respond to the specific antigen in vitro. It was also demonstrated that normal bone marrow cells incubated with antigen are capable of forming antibody which could be detected by the fluorescent antibody technique. This response of the bone marrow cells has been localized to the lymphocyte-rich fraction of the bone marrow. It is concluded that the bone marrow lymphocyte, by virtue of its capacity to react with blastogenesis and mitosis and with antibody formation upon initial exposure to the antigen, a capacity not possessed by lymphocytes of the other lymphoid organs, has a preeminent role in the sequence of cellular events culminating in antibody formation.

Animals↗
PubMed1968

Determination of root exudates in a steril continuous flow culture. I. The culture method.

A sterile plant culture consisting of culture vessels, culture solution container, collecting flasks for percolating nutrient solution, illumination and aeration systems and a suitable pump is described. Its difference with other culture methods is a very slow, continuous percolation of the nutrient solution through the rooting medium. Well defined and controllable conditions can thus be established in the rhizosphere over long culture periods. Samples can be collected at short intervals without disturbing the rhizosphere in any way nor endangering the sterility of the culture. One of the fundamental factors determining the special ecological characteristics of the plant rhizosphere is the liberation of organic and inorganic substances by the plant root. During the study of this phenomenon it became evident that the amount of substances liberated varies within wide limits (factors 100 to 1000) according to the conditions in which the root is developing.

Journal Article↗
PubMed1968

Determination of Root Exudates in a Steril Continuous Flow Culture. II. Short-Term and Long-Term Variations of Exudation Intensity.

The exudate production of alfalfa under the conditions of the sterile flow culture was quantitatively measured. In the first 40 days 3.10(-3) mumoles amino-N, 2.5 muequivalents of organic acids and approximately 10(-4) mumoles of reducing sugars were liberated per plant and per day into the percolating nutrient solution. The amino acid concentration in the outflow varies according to a daily periodicity. The exudation of a colored substance also shows daily periodical variations. This pattern is different from the pattern of the amino acid exudation, however, and directly coupled to shoot illumination. Short-term 2,4-dinitrophenol additions to the nutrient lower the liberation of amino acids into the percolating solution.

Journal Article↗