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Biomedical subjects

M Tavassoli

Publications and source records attributed to M Tavassoli.

At least 271 records · Page 15Linked to original sources
PubMed1975

Thrombocytopenia associated with gold therapy. Observations on the mechanism of platelet destruction.

Severe thrombocytopenia developed in a patient with rheumatoid arthritis during gold therapy. Increased numbers of marrow megakaryocytes, shortened 51Cr-labeled platelet survival and platelet phagocytosis by splenic macrophages indicated that thrombocytopenia was due to excessive platelet destruction. Aurothiomalate disodium antigenicity was demonstrated by increased lymphocyte blastogenesis, and accentuation of blood and splenic leukocyte migration in the presence of the gold salt. In vitro splenic immunoglobulin G (IgG) production was markedly increased, and a significant portion of the culture-produced IgG attached specifically to homologous platelets and platelet membranes. Serum antiplatelet antibodies could not be demonstrated, nor could it be shown that gold enhanced the binding of splenic-synthesized IgG to platelets. The data indicate an immunologic mechanism for gold-associated thrombocytopenia and permit speculation as to possible ways in which unidentified antigens may be involved in the pathogenesis in idiopathic thrombocytopenic purpura.

Antigens↗
PubMed1975

Differential characterization of the "reticulum cell" in lymphoreticular neoplasms.

Differential characterization of the "reticulum cell" in lymphoreticular neoplasms. Am J Clin Pathol. 64: 171-179, 1975. The term "reticulum cell" is confusing, having been applied to the cells involved in many hematopoietic neoplasms, such as reticulum-cell sarcoma, histiocytic medullary reticulosis, leukemic reticuloendotheliosis, and monocytic or histiocytic leukemias. In histologic sections, even the cells from poorly differentiated extramedullary lesions of chloroma or myeloblastic leukemia have been called "reticulum cells."A combined morphologic and cytochemical approach has been used to study "reticulum cells"in smears and tissue sections of neoplasms involving "histiocytes" or "reticulum cells."The cytochemical markers are: chloracetate esterase for neutrophilic granulocytes; nonspecific esterase and fluoride-resistant esterase for monocytes and histiocytes (phagocytes); tartrate-resistant acid phosphatase for the reticulum cells of leukemic reticuloendotheliosis; pyronin for the lymphatic reticulum cells (germinal center cells). The morphology of these cells is very well appreciated in smears, and the locations of these marked cells in tissue sections are easily recognized. The use of cytochemical and immunochemical methods and functional studies, in addition to simple morphology, may be useful in subclassification of lymphoreticular neoplasms.

Cell Differentiation↗
PubMed1975

Structure of the spleen in idiopathic thrombocytopenic purpura.

The structure of the spleens of 12 patients with idiopathic thrombocytopenic purpura (ITP) who underwent splenectomy was studied. The white pulp was characterized by the presence of large numbers of lymphatic nodules containing highly reactive germinal centers. The marginal zone contained large numbers of vessels surrounded by plasma cells. These findings imply active antibody production and are consistent with the concept that the spleen is a major source of antiplatelet antibody production in ITP. Large numbers of platelets in various stages of degradation were seen in cords, particularly in the marginal zone. They appeared both extracellularly and with the cytoplasm of macrophages. It appeared that platelet destruction was initiated by focal cytoplasmic degradation and resulted in formation of cellular debris. These findings indicate that the spleen plays a fundamental role in the pathogenesis of ITP, involving synthesis of antiplatelet antibody, localization of platelets in a milieu rich in this antibody, and subsequently, phagocytosing of immune-damaged platelets.

Adolescent↗
PubMed1975

Cellular and subcellular localization of heme and hemopexin in the rabbit.

The cellular distribution of intravenously administered 3H-heme, 125I-hemopexin and 125I-albumin was studied in rabbits. Radioautography of the tissue slides of several organs was examined by light and electron microscopy. All experiments were terminated 60 min after injection of the isotope-labeled materials. 3H-heme and native monomeric 125I-hemopexin (heme saturated) were found to be associated with the endoplasmic reticulum and microbodies of the hepatocytes. Aggregated hemopexin was also taken up by macrophages of lung alveoli, splenic pulp, interstitial cells of the kidney and Kupffer cells. 125I-albumin (heme saturated) could not be located in liver, spleen, bone marrow, lung, or kidney tissues.

Animals↗
PubMed1975

Erythroblastemia.

The significance of erythroblastemia must be considered in the context of the clinical setting in which it is found. Interpretation should take into account the number and spectrum of maturity of the nucleated red cells; the presence or absence of reticulocytosis and other red cell abnormalities (for example, poikilocytosis); the presence or absence of anemia; the presence or absence of circulating immature granulocytes or bizarre platelets and the presence or absence of the spleen. Circulating nucleated red cells indicate intravascular hemopoiesis or disruption of marrow structure or the inability of the bone marrow's screen mechanism to prevent their passage into circulation. In the latter situations, it usually indicates an unfavorable prognosis.

Anemia, Hemolytic↗
PubMed1975

Limitation of splenic growth as studied by heterotopic splenic implants.

Multiple spleens were implanted in the subcutaneous tissue or the peritoneal cavity of inbred rats which had undergone splenectomy. The total weight of regenerated implants was compared to the weight of implanted tissue. The weight of recovered tissue was not a function of implanted spleen mass; rather, it approximated the unit ratio of the animal's own spleen. Those animals receiving more than ten spleens died by days 3-6 postimplantation, probably as a result of massive necrosis that occurred during the process of regeneration. When implants were made in a temporal sequence of two spleens every 3 days, the first set was uniformly successful, whereas regeneration was aborted in subsequent sets of implants. These observations are consistent with the conclusion that certain factors control the total mass of spleen in any one animal.

Animals↗