In vivo Transfer of a Thrombopoietic Factor.

Spector, Bertram I.

doi:10.3181/00379727-108-26874

Cited by 37 publications

(12 citation statements)

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“…Thrombopoietic activity was not demonstrable by this method in normal rabbit plasma in the dose range tested. Other investigators similarly have been unable to demonstrate thrombopoietic activity in the blood of normal animals when the recipient and donor animals were of the same species (13,51,52).…”

Section: Resultsmentioning

confidence: 99%

“…These phenomena are compatible with a feedback mechanism. Injection of plasma from thrombocytopenic animals has not regularly caused measurable increases in the platelet counts of normal recipients (13,14). However, platelet counts do not necessarily reflect alterations in rate of production since the concentration of circulating cells in the blood is the resultant of the rate of production and of the rate of destruction.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of thrombopoiesis in rabbits using 75selenomethionine

Evatt¹,

Levin²

1969

J. Clin. Invest.

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A B S T R A C T Incorporation of 'selenomethionine ('SeM) has been used to study platelet production in rabbits. Radioactivity of platelets was low after the intravenous administration of 'SeM and rose to a maximum approximately 3 days after administration. Platelet radioactivity was independent of concurrent plasma levels. The life span of rabbit platelets, as estimated with this technique, was 4-5 days. In vivo reutilization of '7SeM previously incorporated into plasma proteins was not detected. In vitro incorporation of 'SeM by platelets in platelet-rich plasma was not demonstrated.Acute hemorrhage 24 hr before administration of 'SeM increased the incorporation of 'SeM into platelets. Transfusion-induced thrombocytosis reduced the incorporation of 'SeM to approximately 30% of that observed in control animals. Suppression of bone marrow function with nitrogen mustard resulted in decreased numbers of platelets in the circulation, and a decrease in incorporation of 'SeM. Delayed appearance of '7SeM was observed in circulating platelets during recovery from marrow suppression. Injection of 75-225 ml of plasma from thrombocytopenic donors into normal rabbits increased incorporation of 'SeM into platelets while normal plasma did not have this effect.The rate of appearance of 'SeM in circulating platelets appears to provide a sensitive and specific method for the study of production of platelets by megakaryocytes. The data suggest more rapid entry of platelets into the circulation, and a sustained increase in incorporation of 'SeM into platelet protein after stimulation of platelet production. The results are consistent with the concept of a humoral agent (thrombopoietin) that acts on megakaryocytes to regulate platelet production.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of thrombopoiesis in rabbits using 75selenomethionine

Evatt¹,

Levin²

1969

J. Clin. Invest.

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“…Several investigators have found similar platelet elevating activity in normal, "anemic" and thrombocytopenic plasmas (Linman & Pierre 1962, Linman 1962, Odell et al 1961, Spector 1961, Steinberg et al 1959, Schulman 1960. The spleen extract is similar to Linman's boiled plasma preparation in that both are stable to heat and acid pH and are effective after oral administration; however, the spleen extract differs in that it brings about a change in the platelet count during a single turnover of the megakaryocyte population, rather than requiring multiple administration over a two week period.…”

Section: Discussionmentioning

confidence: 93%

Studies on Thrombopoiesis II Effect of a Non‐Dialyzable Spleen Preparation on the Thrombocyte Level

Cooney

Blatt

Louis-Ferdinand

et al. 1965

Scandinavian Journal of Haematology

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Evidence is presented for the presence in normal bovine and canine spleen of a material that elevates the platelet count of rabbits. An extraction method and bioassay are outlined. The spleen extract is non‐dialyzable, heat and pH resistant, and exhibits an absorption peak at 265 mμ. It is postulated that the extract effects new platelet production by causing the differentiation of precursor cells to megakaryoblasts. Activity was also found in red cells and platelets but not in a variety of other bovine organs.

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“…O dell's (13), Spector's (8) and our studies of passive transfer of the thrombocytic factor and the appearance of the thrombocytic in trinsic factor upon stimulation should help to clarify the role of non specific materials. Transfer of serum from donor rabbits injected with 'non-specific substances' have shown presence of intrinsic thrombocytosis factor on the 5th day as with thrombocytic factor of serum.…”

Section: Discussionmentioning

confidence: 99%