Biomedical subjects

C Adrados

Publications and source records attributed to C Adrados.

5 recordsLinked to original sources

PubMed1986

Functionally abnormal stromal cells and megakaryocyte size, ploidy, and ultrastructure in Sl/Sld mice.

The first goal of the present studies was to determine if Sl/Sld megakaryocytes have features in common with the macrocytic megakaryocytes that genetically normal mice produce in response to acute platelet depletion. The second was to test the hypothesis that megakaryocyte abnormalities in Sl/Sld mice are due to genetically determined hemopoietic stromal cell abnormalities. Sizes and ploidies of mature Sl/Sld megakaryocytes were measured. Macrocytosis and a shift to higher ploidy values were found compared with normal. Within ploidy groups 16N-64N, Sl/Sld megakaryocytes were larger than normal megakaryocytes of the same ploidy. Transmission electron microscopy revealed that Sl/Sld megakaryocyte nuclei contain more and larger nucleoli, and the chromatin was more dispersed than in normal megakaryocyte nuclei of comparable maturity. Asynchronous megakaryocyte cytoplasmic maturation was found. Sl/Sld macrophages were also ultrastructurally abnormal. Megakaryocytic macrocytosis was reproduced in long-term bone marrow cultures in which the adherent layer was formed by Sl/Sld cells. It was the same if cultures were recharged with Sl/Sld or +/+ hemopoietic cells. Previously reported ambiguities in mixed cell cultures were avoided by recharging the adherent layers with only a million cells. These results were correlated with previously published observations. Sl/Sld megakaryocytes have features in common with megakaryocytes from acutely thrombocytopenic animals. One feature, macrocytosis, appears to be due to abnormal Sl/Sld stromal cells that are reproduced as adherent layer cells in long-term cultures. The responsible stromal cells in Sl/Sld mice may be counterparts of megakaryocytopoietic regulatory cells in the marrow stroma of normal animals.

Animals↗

PubMed1985

Independence of megakaryocyte number and size in long-term cultures of normal mouse marrow.

Megakaryocytopoiesis was evaluated in long-term cultures of normal murine marrow to determine whether the number and size of megakaryocytes were independent or interdependent. Numbers of megakaryocytes and granulocytes varied widely in different experiments, due, in part, to varying concentrations of hydrocortisone in the culture medium. The sizes of acetylcholinesterase-positive cells were the same in cultures with as much as a 20-fold difference in megakaryocyte numbers. These results indicate that, in the closed culture system containing normal stromal cells, megakaryocyte size and number are not reciprocal as they were in many previously reported cultures of S1/S1d mouse marrow. The results suggest that separate stromal functions may determine precursor cell proliferation and nuclear endomitosis in megakaryocytes in vitro. The relationship of these findings to regulation of megakaryocytopoiesis in vivo remains speculative.

Acetylcholinesterase↗

PubMed1984

Mean platelet volume: the need for a reference method.

The time course of artifactual effects due to anticoagulants, specimen temperature, and interval between venipuncture and analysis on platelet volume measurements was evaluated. Split specimens were analyzed using hydrodynamic focusing, and platelet distributions were computed using a least-squares fit to a log-normal distribution. Significant artifacts resulted from exposure to EDTA, cooling to room temperature, and delay in exposure to anticoagulant. The artifactual effect of EDTA is extreme and time dependent. Collection of blood in Buffered Citrate, Acid Citrate Dextrose, or Pyridoxal-5'-phosphate supplemented Citrate yielded stable and equivalent results with rapid anticoagulation and incubation at 37 degrees C for up to six hours.

Anticoagulants↗

PubMed1984

Macrocytic megakaryocytes in cultures of S1/S1d bone marrow.

The thrombocytopoietic system of S1/S1d mice is characterized by macromegakaryocytosis and megakaryocytopenia, but the mechanisms responsible for reciprocal abnormalities of megakaryocyte number and size are unknown. These mice have a genetically determined abnormality of their hemopoietic microenvironment that can, in part, be reproduced as abnormal adherent stromal cells in bone marrow cultures. Cultures of bone marrow were therefore done to determine if the megakaryocytic abnormalities of S1/S1d marrow would also be reproduced in them. Cultures composed entirely of S1/S1d cells showed persistent macrocytosis of megakaryocytes when compared with cultures of normal +/+ marrow. At various times of culture, there were also reduced numbers of megakaryocytes, total cells, and granulocytes in the supernatants of S1/S1d cultures. Mixed cultures of S1/S1d and +/+ cells yielded inconclusive findings. The fact that macromegakaryocytosis occurred in cultures of S1/S1d marrow strongly suggests that its in vivo determinants were, in part, reproduced in culture.

Acetylcholinesterase↗

PubMed1981

Megakaryocytopoiesis in irradiated, splenectomized mice.

The hypomegakaryocytic state that develops after exposure to sublethal doses of ionizing radiation was evaluated in splenectomized and intact mice. The percentage reduction of marrow megakaryocytes was greater than that of platelets at comparable times post-irradiation. After initial recovery a secondary drop in platelet counts occurred earlier in intact than in splenectomized mice. The average size of mature megakaryocytes was found to be increased, due primarily to marked reductions in megakaryocytes of smaller size. These results indicate that the spleen acts more to reduce than to increase the platelet count after exposure to sublethal doses of whole body radiation and that megakaryocyte size may be increased by reduction in numbers of small megakaryocytes without an increase in large megakaryocytes.

Animals↗