PubMed · 3990791
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Embryo research.. https://pubmed.ncbi.nlm.nih.gov/3990791/
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We have shown for the first time that the microsomal glucose-6-phosphatase enzyme protein is present in human embryonic and fetal red blood cells and the ontogeny of its expression has been determined. In the earliest embryos, red cells are predominantly of the primitive megaloblastic type. Circulating red cells in the primitive megaloblastic series are predominantly nucleated and glucose-6-phosphatase immunopositive. Non-nucleated, immunoreactive megaloblastic cells are in a minority. In fetuses > 12 weeks gestation, the erythrocytes are of the definitive normoblastic series and in the transitional period of switch-over in late embryonic-early fetal life, up to 30% of glucose-6-phosphatase immunopositive cells are definitive normoblastic in type, with a variable contribution from nucleated and non-nucleated cells. Thereafter, the number of immunopositive cells in the definitive normoblastic series decreases such that after 12 weeks gestation it is less than 5%. The fact that a predominantly hepatic protein in adults (glucose-6-phosphatase) is present in embryonic and fetal red blood cells, particularly nucleated red cells, raises the possibility of diagnosis of disorders of liver protein expression in nucleated fetal red cells isolated from the first trimester maternal circulation.
The presented study investigates the time-dependent release of PGI2 and TXA2 by isolated human umbilical veins in vitro using the radioimmunoassay for measurement. After changing the nutritional fluid--Krebs-Henseleit solution at pH 7.4, 37 degrees C, 95% O2/5% CO2--the release graph oscillates. These oscillations with time were verified by variance analysis and are very similar for both substances. This indicates one or several negative feedback mechanisms acting on the common path of synthesis from the membrane-bound phospholipids to PGH2, which are effective in the regulation of eicosanoid biosynthesis in vitro. A mathematical function describing the observed PGI2 and TXA2 synthesis is communicated.
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