In Vivo Labeling of Platelets with 75Se – Selenomethionine in Patients with Hepatic Cirrhosis and Thrombocytopenia.

Abstract

SummaryLabeling of platelets in vivo by 75Se – Selenomethionine (75Se-M) was performed in nine cases of hepatic cirrhosis and thrombocytopenia for evaluation of the kinetics of platelet maturation. Folic acid and vitamin B12 deficiency was excluded by pretreatment of the patients with these agents. The platelet maturation time – time between the injection of the isotope and maximum radioactivity of separated blood platelets – was shortened to 7.7±1.1 days (mean±SD) compared to the normal of 9.1±1.4 days. For explanation a disturbance of megakaryocyte maturation and/or platelet release from the bone marrow is suggested.

Megathrombocytes, Platelet Regeneration Time and Platelet-Associated IgG in Idiopathic Thrombocytopenic Purpura and in Thrombocytopenia Associated with Chronic Liver Disease

“…An increased platelet turnover has been found frequently in patients with liver disease and thrombo cytopenia [13,24] and this has been attrib uted to splenic pooling and to intravascular coagulation [13].…”

⁷⁵SE-Methionine Platelet Survival Studies: a Proposal for a Mathematical Correction of the Curve

“…50% of the descending slope has been obtained only on day 20.8 and in patient 3 (female; table I) the survival time was not computable. A slow decrease in the platelet radioactivity has been reported by Mayer et al [14], who were unable to compute the platelet survival time in 6 of 9 patients. This behaviour has been reported by others using 75Se-methionine [2,4,5,14,15],…”

“…Other authors, using a manual plot, have obtained results varying from 4 to 10 days [2,4,5,14] and from 5 to 7 days [15], In the catabolic phase of the curve, the pattern shows great individual variability. 50% of the descending slope has been obtained only on day 20.8 and in patient 3 (female; table I) the survival time was not computable.…”

“…Two isotopic approaches have been employed so far in the study of platelet survival. The first consists in the 'cohort' labelling of platelets [10], the other consists in the 'random' labelling of a mixed circulat ing platelet population [10], Since 32P-orthophosphate and l4C-serotonin proved unsatis factory for the random labelling due to in vivo release and reutilization [8,9], the pro cedure recommended by ICSH [12] is the in vitro labelling with 5lCr [8,11,16,19,21], For the cohort labelling 32DFP [1,22], 35S and 75Se-methionine [2,14,15] have been used. 75Se-methionine, e.g., is directly incorpo rated into megakaryocytes and can be dem onstrated in the platelets after release from the bone marrow [2,7], This technique of labelling has the advantage of being easier than 5lCr labelling and of supplying informa tion on platelet maturation time.…”

“…75Se-methionine, e.g., is directly incorpo rated into megakaryocytes and can be dem onstrated in the platelets after release from the bone marrow [2,7], This technique of labelling has the advantage of being easier than 5lCr labelling and of supplying informa tion on platelet maturation time. However, the disappearance of 75Se-methionine-labelled platelets from the circulation is com plicated by the plasmatic 75Se-methionine pool reuptake [2,14,15]; consequently plate let removal proceeds concurrently with the appearance of newly labelled cells from the bone marrow into the circulation [2,14,15]. A mathematical computerized analysis of 75Se-methionine platelet survival curves has been studied in an attempt to overcome the limits of this labelling technique.…”